diff --git a/src/LegacyCallHandler.tsx b/src/LegacyCallHandler.tsx
index 97cb478512..9c3e7073d5 100644
--- a/src/LegacyCallHandler.tsx
+++ b/src/LegacyCallHandler.tsx
@@ -679,7 +679,7 @@ export default class LegacyCallHandler extends TypedEventEmitter<LegacyCallHandl
 
     private showICEFallbackPrompt(): void {
         const cli = MatrixClientPeg.safeGet();
-        Modal.createDialog(
+        const { finished } = Modal.createDialog(
             QuestionDialog,
             {
                 title: _t("voip|misconfigured_server"),
@@ -703,13 +703,14 @@ export default class LegacyCallHandler extends TypedEventEmitter<LegacyCallHandl
                     server: new URL(FALLBACK_ICE_SERVER).pathname,
                 }),
                 cancelButton: _t("action|ok"),
-                onFinished: (allow) => {
-                    SettingsStore.setValue("fallbackICEServerAllowed", null, SettingLevel.DEVICE, allow);
-                },
             },
             undefined,
             true,
         );
+
+        finished.then(([allow]) => {
+            SettingsStore.setValue("fallbackICEServerAllowed", null, SettingLevel.DEVICE, allow);
+        });
     }
 
     private showMediaCaptureError(call: MatrixCall): void {
diff --git a/src/Lifecycle.ts b/src/Lifecycle.ts
index c1559886b4..6f78c01357 100644
--- a/src/Lifecycle.ts
+++ b/src/Lifecycle.ts
@@ -469,12 +469,15 @@ type TryAgainFunction = () => void;
  * @param tryAgain OPTIONAL function to call on try again button from error dialog
  */
 function onFailedDelegatedAuthLogin(description: string | ReactNode, tryAgain?: TryAgainFunction): void {
-    Modal.createDialog(ErrorDialog, {
+    const { finished } = Modal.createDialog(ErrorDialog, {
         title: _t("auth|oidc|error_title"),
         description,
         button: _t("action|try_again"),
+    });
+
+    finished.then(([shouldTryAgain]) => {
         // if we have a tryAgain callback, call it the primary 'try again' button was clicked in the dialog
-        onFinished: tryAgain ? (shouldTryAgain?: boolean) => shouldTryAgain && tryAgain() : undefined,
+        if (shouldTryAgain) tryAgain?.();
     });
 }
 
diff --git a/src/Modal.tsx b/src/Modal.tsx
index ba5c6702bd..cd6c6a3255 100644
--- a/src/Modal.tsx
+++ b/src/Modal.tsx
@@ -30,12 +30,25 @@ export type ComponentType =
       }>
     | React.ComponentType<any>;
 
-// Generic type which returns the props of the Modal component with the onFinished being optional.
+/**
+ * The parameter types of the `onFinished` callback property exposed by the component which forms the
+ * body of the dialog.
+ *
+ * @typeParam C - The type of the React component which forms the body of the dialog.
+ */
+type OnFinishedParams<C extends ComponentType> = Parameters<React.ComponentProps<C>["onFinished"]>;
+
+/**
+ * The properties exposed by the `props` argument to {@link Modal.createDialog}: the same as
+ * those exposed by the underlying component, with the exception of `onFinished`, which is provided by
+ * `createDialog`.
+ *
+ * @typeParam C - The type of the React component which forms the body of the dialog.
+ */
 export type ComponentProps<C extends ComponentType> = Defaultize<
     Omit<React.ComponentProps<C>, "onFinished">,
     C["defaultProps"]
-> &
-    Partial<Pick<React.ComponentProps<C>, "onFinished">>;
+>;
 
 export interface IModal<C extends ComponentType> {
     elem: React.ReactNode;
@@ -43,15 +56,44 @@ export interface IModal<C extends ComponentType> {
     beforeClosePromise?: Promise<boolean>;
     closeReason?: ModalCloseReason;
     onBeforeClose?(reason?: ModalCloseReason): Promise<boolean>;
-    onFinished: ComponentProps<C>["onFinished"];
-    close(...args: Parameters<ComponentProps<C>["onFinished"]>): void;
+
+    /**
+     * Run the {@link deferred} with the given arguments, and close this modal.
+     *
+     * This method is passed as the `onFinished` callback to the underlying component,
+     * as well as being returned by {@link Modal.createDialog} to the caller.
+     */
+    close(...args: OnFinishedParams<C> | []): void;
+
     hidden?: boolean;
-    deferred?: IDeferred<Parameters<ComponentProps<C>["onFinished"]>>;
+
+    /** A deferred to resolve when the dialog closes, with the results as provided by
+     * the call to {@link close} (normally from the `onFinished` callback).
+     */
+    deferred?: IDeferred<OnFinishedParams<C> | []>;
 }
 
+/** The result of {@link Modal.createDialog}.
+ *
+ * @typeParam C - The type of the React component which forms the body of the dialog.
+ */
 export interface IHandle<C extends ComponentType> {
-    finished: Promise<Parameters<ComponentProps<C>["onFinished"]>>;
-    close(...args: Parameters<ComponentProps<C>["onFinished"]>): void;
+    /**
+     * A promise which will resolve when the dialog closes.
+     *
+     * If the dialog body component calls the `onFinished` property, or the caller calls {@link close},
+     * the promise resolves with an array holding the arguments to that call.
+     *
+     * If the dialog is closed by clicking in the background, the promise resolves with an empty array.
+     */
+    finished: Promise<OnFinishedParams<C> | []>;
+
+    /**
+     * A function which, if called, will close the dialog.
+     *
+     * @param args - Arguments to return to {@link finished}.
+     */
+    close(...args: OnFinishedParams<C>): void;
 }
 
 interface IOptions<C extends ComponentType> {
@@ -164,7 +206,6 @@ export class ModalManager extends TypedEventEmitter<ModalManagerEvent, HandlerMa
         const modals = filterBoolean([...this.modals, this.staticModal, this.priorityModal]);
         for (const modal of modals) {
             modal.deferred?.resolve([]);
-            if (modal.onFinished) modal.onFinished.apply(null);
             this.emitClosed();
         }
 
@@ -188,7 +229,6 @@ export class ModalManager extends TypedEventEmitter<ModalManagerEvent, HandlerMa
         onFinishedProm: IHandle<C>["finished"];
     } {
         const modal = {
-            onFinished: props?.onFinished,
             onBeforeClose: options?.onBeforeClose,
             className,
 
@@ -196,8 +236,7 @@ export class ModalManager extends TypedEventEmitter<ModalManagerEvent, HandlerMa
             elem: null,
         } as IModal<C>;
 
-        // never call this from onFinished() otherwise it will loop
-        const [closeDialog, onFinishedProm] = this.getCloseFn<C>(modal, props);
+        const [closeDialog, onFinishedProm] = this.getCloseFn<C>(modal);
 
         // don't attempt to reuse the same AsyncWrapper for different dialogs,
         // otherwise we'll get confused.
@@ -214,13 +253,10 @@ export class ModalManager extends TypedEventEmitter<ModalManagerEvent, HandlerMa
         return { modal, closeDialog, onFinishedProm };
     }
 
-    private getCloseFn<C extends ComponentType>(
-        modal: IModal<C>,
-        props?: ComponentProps<C>,
-    ): [IHandle<C>["close"], IHandle<C>["finished"]] {
-        modal.deferred = defer<Parameters<ComponentProps<C>["onFinished"]>>();
+    private getCloseFn<C extends ComponentType>(modal: IModal<C>): [IHandle<C>["close"], IHandle<C>["finished"]] {
+        modal.deferred = defer<OnFinishedParams<C> | []>();
         return [
-            async (...args: Parameters<ComponentProps<C>["onFinished"]>): Promise<void> => {
+            async (...args: OnFinishedParams<C>): Promise<void> => {
                 if (modal.beforeClosePromise) {
                     await modal.beforeClosePromise;
                 } else if (modal.onBeforeClose) {
@@ -232,7 +268,6 @@ export class ModalManager extends TypedEventEmitter<ModalManagerEvent, HandlerMa
                     }
                 }
                 modal.deferred?.resolve(args);
-                if (props?.onFinished) props.onFinished.apply(null, args);
                 const i = this.modals.indexOf(modal);
                 if (i >= 0) {
                     this.modals.splice(i, 1);
@@ -280,7 +315,8 @@ export class ModalManager extends TypedEventEmitter<ModalManagerEvent, HandlerMa
      *                  using React.lazy to async load the component.
      *                  e.g. `lazy(() => import('./MyComponent'))`
      *
-     * @param props properties to pass to the displayed component. (We will also pass an 'onFinished' property.)
+     * @param props properties to pass to the displayed component. (We will also pass an `onFinished` property; when
+     *     called, that property will close the dialog and return the results to the caller via {@link IHandle.finished}.)
      *
      * @param className CSS class to apply to the modal wrapper
      *
@@ -295,7 +331,7 @@ export class ModalManager extends TypedEventEmitter<ModalManagerEvent, HandlerMa
      *                                 static at a time.
      * @param options? extra options for the dialog
      * @param options.onBeforeClose a callback to decide whether to close the dialog
-     * @returns Object with 'close' parameter being a function that will close the dialog
+     * @returns {@link IHandle} object.
      */
     public createDialog<C extends ComponentType>(
         component: C,
diff --git a/src/Registration.tsx b/src/Registration.tsx
index ea0264fab3..22eb6e15ff 100644
--- a/src/Registration.tsx
+++ b/src/Registration.tsx
@@ -62,14 +62,14 @@ export async function startAnyRegistrationFlow(
                   </button>,
               ]
             : [],
-        onFinished: (proceed) => {
-            if (proceed) {
-                dis.dispatch({ action: "start_login", screenAfterLogin: options.screen_after });
-            } else if (options.go_home_on_cancel) {
-                dis.dispatch({ action: Action.ViewHomePage });
-            } else if (options.go_welcome_on_cancel) {
-                dis.dispatch({ action: "view_welcome_page" });
-            }
-        },
+    });
+    modal.finished.then(([proceed]) => {
+        if (proceed) {
+            dis.dispatch({ action: "start_login", screenAfterLogin: options.screen_after });
+        } else if (options.go_home_on_cancel) {
+            dis.dispatch({ action: Action.ViewHomePage });
+        } else if (options.go_welcome_on_cancel) {
+            dis.dispatch({ action: "view_welcome_page" });
+        }
     });
 }
diff --git a/src/async-components/views/dialogs/security/NewRecoveryMethodDialog.tsx b/src/async-components/views/dialogs/security/NewRecoveryMethodDialog.tsx
index 9b9683b798..a2fef4e1c9 100644
--- a/src/async-components/views/dialogs/security/NewRecoveryMethodDialog.tsx
+++ b/src/async-components/views/dialogs/security/NewRecoveryMethodDialog.tsx
@@ -49,15 +49,8 @@ export default function NewRecoveryMethodDialog({ onFinished }: NewRecoveryMetho
         if (isKeyBackupEnabled) {
             onFinished();
         } else {
-            Modal.createDialog(
-                RestoreKeyBackupDialog,
-                {
-                    onFinished,
-                },
-                undefined,
-                false,
-                true,
-            );
+            const { finished } = Modal.createDialog(RestoreKeyBackupDialog, {}, undefined, false, true);
+            finished.then(onFinished);
         }
     }
 
diff --git a/src/components/structures/MatrixChat.tsx b/src/components/structures/MatrixChat.tsx
index 83d6f5f54c..02a3a55c59 100644
--- a/src/components/structures/MatrixChat.tsx
+++ b/src/components/structures/MatrixChat.tsx
@@ -1229,7 +1229,7 @@ export default class MatrixChat extends React.PureComponent<IProps, IState> {
         const warnings = this.leaveRoomWarnings(roomId);
 
         const isSpace = roomToLeave?.isSpaceRoom();
-        Modal.createDialog(QuestionDialog, {
+        const { finished } = Modal.createDialog(QuestionDialog, {
             title: isSpace ? _t("space|leave_dialog_action") : _t("action|leave_room"),
             description: (
                 <span>
@@ -1245,16 +1245,17 @@ export default class MatrixChat extends React.PureComponent<IProps, IState> {
             ),
             button: _t("action|leave"),
             danger: warnings.length > 0,
-            onFinished: async (shouldLeave) => {
-                if (shouldLeave) {
-                    await leaveRoomBehaviour(cli, roomId);
+        });
 
-                    dis.dispatch<AfterLeaveRoomPayload>({
-                        action: Action.AfterLeaveRoom,
-                        room_id: roomId,
-                    });
-                }
-            },
+        finished.then(async ([shouldLeave]) => {
+            if (shouldLeave) {
+                await leaveRoomBehaviour(cli, roomId);
+
+                dis.dispatch<AfterLeaveRoomPayload>({
+                    action: Action.AfterLeaveRoom,
+                    room_id: roomId,
+                });
+            }
         });
     }
 
@@ -1558,7 +1559,7 @@ export default class MatrixChat extends React.PureComponent<IProps, IState> {
             });
         });
         cli.on(HttpApiEvent.NoConsent, function (message, consentUri) {
-            Modal.createDialog(
+            const { finished } = Modal.createDialog(
                 QuestionDialog,
                 {
                     title: _t("terms|tac_title"),
@@ -1569,16 +1570,16 @@ export default class MatrixChat extends React.PureComponent<IProps, IState> {
                     ),
                     button: _t("terms|tac_button"),
                     cancelButton: _t("action|dismiss"),
-                    onFinished: (confirmed) => {
-                        if (confirmed) {
-                            const wnd = window.open(consentUri, "_blank")!;
-                            wnd.opener = null;
-                        }
-                    },
                 },
                 undefined,
                 true,
             );
+            finished.then(([confirmed]) => {
+                if (confirmed) {
+                    const wnd = window.open(consentUri, "_blank")!;
+                    wnd.opener = null;
+                }
+            });
         });
 
         DecryptionFailureTracker.instance
diff --git a/src/components/structures/RoomView.tsx b/src/components/structures/RoomView.tsx
index 0a27dd4f4e..fbff50bd01 100644
--- a/src/components/structures/RoomView.tsx
+++ b/src/components/structures/RoomView.tsx
@@ -1753,7 +1753,7 @@ export class RoomView extends React.Component<IRoomProps, IRoomState> {
         }
 
         if (reportRoom !== false) {
-            actions.push(this.context.client.reportRoom(this.state.room.roomId, reportRoom));
+            actions.push(this.context.client.reportRoom(this.state.room.roomId, reportRoom!));
         }
 
         actions.push(this.context.client.leave(this.state.room.roomId));
diff --git a/src/components/structures/TimelinePanel.tsx b/src/components/structures/TimelinePanel.tsx
index a523754c41..8346a0ab31 100644
--- a/src/components/structures/TimelinePanel.tsx
+++ b/src/components/structures/TimelinePanel.tsx
@@ -1505,11 +1505,13 @@ class TimelinePanel extends React.Component<IProps, IState> {
                 description = _t("timeline|load_error|unable_to_find");
             }
 
-            Modal.createDialog(ErrorDialog, {
+            const { finished } = Modal.createDialog(ErrorDialog, {
                 title: _t("timeline|load_error|title"),
                 description,
-                onFinished,
             });
+            if (onFinished) {
+                finished.then(onFinished);
+            }
         };
 
         // if we already have the event in question, TimelineWindow.load
diff --git a/src/components/structures/auth/SetupEncryptionBody.tsx b/src/components/structures/auth/SetupEncryptionBody.tsx
index ee8dce4c58..b76a623e2c 100644
--- a/src/components/structures/auth/SetupEncryptionBody.tsx
+++ b/src/components/structures/auth/SetupEncryptionBody.tsx
@@ -90,14 +90,15 @@ export default class SetupEncryptionBody extends React.Component<IProps, IState>
         // We need to call onFinished now to close this dialog, and
         // again later to signal that the verification is complete.
         this.props.onFinished();
-        Modal.createDialog(VerificationRequestDialog, {
+        const { finished: verificationFinished } = Modal.createDialog(VerificationRequestDialog, {
             verificationRequestPromise: requestPromise,
             member: cli.getUser(userId) ?? undefined,
-            onFinished: async (): Promise<void> => {
-                const request = await requestPromise;
-                request.cancel();
-                this.props.onFinished();
-            },
+        });
+
+        verificationFinished.then(async () => {
+            const request = await requestPromise;
+            request.cancel();
+            this.props.onFinished();
         });
     };
 
diff --git a/src/components/structures/auth/SoftLogout.tsx b/src/components/structures/auth/SoftLogout.tsx
index 68fe65aedc..34fabe46c7 100644
--- a/src/components/structures/auth/SoftLogout.tsx
+++ b/src/components/structures/auth/SoftLogout.tsx
@@ -89,13 +89,12 @@ export default class SoftLogout extends React.Component<IProps, IState> {
     }
 
     private onClearAll = (): void => {
-        Modal.createDialog(ConfirmWipeDeviceDialog, {
-            onFinished: (wipeData) => {
-                if (!wipeData) return;
+        const { finished } = Modal.createDialog(ConfirmWipeDeviceDialog);
+        finished.then(([wipeData]) => {
+            if (!wipeData) return;
 
-                logger.log("Clearing data from soft-logged-out session");
-                Lifecycle.logout(this.context.oidcClientStore);
-            },
+            logger.log("Clearing data from soft-logged-out session");
+            Lifecycle.logout(this.context.oidcClientStore);
         });
     };
 
diff --git a/src/components/views/auth/RegistrationForm.tsx b/src/components/views/auth/RegistrationForm.tsx
index 783c15ed3f..88e9aa0615 100644
--- a/src/components/views/auth/RegistrationForm.tsx
+++ b/src/components/views/auth/RegistrationForm.tsx
@@ -127,19 +127,11 @@ export default class RegistrationForm extends React.PureComponent<IProps, IState
 
         if (this.state.email === "") {
             if (this.showEmail()) {
-                Modal.createDialog(RegistrationEmailPromptDialog, {
-                    onFinished: async (confirmed: boolean, email?: string): Promise<void> => {
-                        if (confirmed && email !== undefined) {
-                            this.setState(
-                                {
-                                    email,
-                                },
-                                () => {
-                                    this.doSubmit(ev);
-                                },
-                            );
-                        }
-                    },
+                const { finished } = Modal.createDialog(RegistrationEmailPromptDialog);
+                finished.then(async ([confirmed, email]) => {
+                    if (confirmed && email !== undefined) {
+                        this.setState({ email }, () => this.doSubmit(ev));
+                    }
                 });
             } else {
                 // user can't set an e-mail so don't prompt them to
diff --git a/src/components/views/context_menus/DeveloperToolsOption.tsx b/src/components/views/context_menus/DeveloperToolsOption.tsx
index fc77a2e284..53a5d7283d 100644
--- a/src/components/views/context_menus/DeveloperToolsOption.tsx
+++ b/src/components/views/context_menus/DeveloperToolsOption.tsx
@@ -25,7 +25,6 @@ export const DeveloperToolsOption: React.FC<Props> = ({ onFinished, roomId }) =>
                 Modal.createDialog(
                     DevtoolsDialog,
                     {
-                        onFinished: () => {},
                         roomId: roomId,
                     },
                     "mx_DevtoolsDialog_wrapper",
diff --git a/src/components/views/context_menus/WidgetContextMenu.tsx b/src/components/views/context_menus/WidgetContextMenu.tsx
index 627e0814e2..5b03d54e17 100644
--- a/src/components/views/context_menus/WidgetContextMenu.tsx
+++ b/src/components/views/context_menus/WidgetContextMenu.tsx
@@ -187,14 +187,15 @@ export const WidgetContextMenu: React.FC<IProps> = ({
                 onDeleteClick();
             } else if (roomId) {
                 // Show delete confirmation dialog
-                Modal.createDialog(QuestionDialog, {
+                const { finished } = Modal.createDialog(QuestionDialog, {
                     title: _t("widget|context_menu|delete"),
                     description: _t("widget|context_menu|delete_warning"),
                     button: _t("widget|context_menu|delete"),
-                    onFinished: (confirmed) => {
-                        if (!confirmed) return;
-                        WidgetUtils.setRoomWidget(cli, roomId, app.id);
-                    },
+                });
+
+                finished.then(([confirmed]) => {
+                    if (!confirmed) return;
+                    WidgetUtils.setRoomWidget(cli, roomId, app.id);
                 });
             }
 
diff --git a/src/components/views/dialogs/AnalyticsLearnMoreDialog.tsx b/src/components/views/dialogs/AnalyticsLearnMoreDialog.tsx
index 90681556e8..d80f03b7d4 100644
--- a/src/components/views/dialogs/AnalyticsLearnMoreDialog.tsx
+++ b/src/components/views/dialogs/AnalyticsLearnMoreDialog.tsx
@@ -11,7 +11,7 @@ import React from "react";
 import BaseDialog from "./BaseDialog";
 import { _t } from "../../../languageHandler";
 import DialogButtons from "../elements/DialogButtons";
-import Modal, { type ComponentProps } from "../../../Modal";
+import Modal, { type ComponentProps, type IHandle } from "../../../Modal";
 import SdkConfig from "../../../SdkConfig";
 import { getPolicyUrl } from "../../../toasts/AnalyticsToast";
 import ExternalLink from "../elements/ExternalLink";
@@ -91,10 +91,10 @@ export const AnalyticsLearnMoreDialog: React.FC<IProps> = ({
 
 export const showDialog = (
     props: Omit<ComponentProps<typeof AnalyticsLearnMoreDialog>, "cookiePolicyUrl" | "analyticsOwner">,
-): void => {
+): IHandle<typeof AnalyticsLearnMoreDialog> => {
     const privacyPolicyUrl = getPolicyUrl();
     const analyticsOwner = SdkConfig.get("analytics_owner") ?? SdkConfig.get("brand");
-    Modal.createDialog(
+    return Modal.createDialog(
         AnalyticsLearnMoreDialog,
         {
             privacyPolicyUrl,
diff --git a/src/components/views/dialogs/ConfirmRedactDialog.tsx b/src/components/views/dialogs/ConfirmRedactDialog.tsx
index d3fba9b475..17bf75ccad 100644
--- a/src/components/views/dialogs/ConfirmRedactDialog.tsx
+++ b/src/components/views/dialogs/ConfirmRedactDialog.tsx
@@ -58,37 +58,32 @@ export function createRedactEventDialog({
     const roomId = mxEvent.getRoomId();
 
     if (!roomId) throw new Error(`cannot redact event ${mxEvent.getId()} without room ID`);
-    Modal.createDialog(
-        ConfirmRedactDialog,
-        {
-            event: mxEvent,
-            onFinished: async (proceed, reason): Promise<void> => {
-                if (!proceed) return;
+    const { finished } = Modal.createDialog(ConfirmRedactDialog, { event: mxEvent }, "mx_Dialog_confirmredact");
 
-                const cli = MatrixClientPeg.safeGet();
-                const withRelTypes: Pick<IRedactOpts, "with_rel_types"> = {};
+    finished.then(async ([proceed, reason]) => {
+        if (!proceed) return;
 
-                try {
-                    onCloseDialog?.();
-                    await cli.redactEvent(roomId, eventId, undefined, {
-                        ...(reason ? { reason } : {}),
-                        ...withRelTypes,
-                    });
-                } catch (e: any) {
-                    const code = e.errcode || e.statusCode;
-                    // only show the dialog if failing for something other than a network error
-                    // (e.g. no errcode or statusCode) as in that case the redactions end up in the
-                    // detached queue and we show the room status bar to allow retry
-                    if (typeof code !== "undefined") {
-                        // display error message stating you couldn't delete this.
-                        Modal.createDialog(ErrorDialog, {
-                            title: _t("common|error"),
-                            description: _t("redact|error", { code }),
-                        });
-                    }
-                }
-            },
-        },
-        "mx_Dialog_confirmredact",
-    );
+        const cli = MatrixClientPeg.safeGet();
+        const withRelTypes: Pick<IRedactOpts, "with_rel_types"> = {};
+
+        try {
+            onCloseDialog?.();
+            await cli.redactEvent(roomId, eventId, undefined, {
+                ...(reason ? { reason } : {}),
+                ...withRelTypes,
+            });
+        } catch (e: any) {
+            const code = e.errcode || e.statusCode;
+            // only show the dialog if failing for something other than a network error
+            // (e.g. no errcode or statusCode) as in that case the redactions end up in the
+            // detached queue and we show the room status bar to allow retry
+            if (typeof code !== "undefined") {
+                // display error message stating you couldn't delete this.
+                Modal.createDialog(ErrorDialog, {
+                    title: _t("common|error"),
+                    description: _t("redact|error", { code }),
+                });
+            }
+        }
+    });
 }
diff --git a/src/components/views/dialogs/SessionRestoreErrorDialog.tsx b/src/components/views/dialogs/SessionRestoreErrorDialog.tsx
index 26baef9f2a..edf93558ff 100644
--- a/src/components/views/dialogs/SessionRestoreErrorDialog.tsx
+++ b/src/components/views/dialogs/SessionRestoreErrorDialog.tsx
@@ -31,13 +31,13 @@ export default class SessionRestoreErrorDialog extends React.Component<IProps> {
     };
 
     private onClearStorageClick = (): void => {
-        Modal.createDialog(QuestionDialog, {
+        const { finished } = Modal.createDialog(QuestionDialog, {
             title: _t("action|sign_out"),
             description: <div>{_t("error|session_restore|clear_storage_description")}</div>,
             button: _t("action|sign_out"),
             danger: true,
-            onFinished: this.props.onFinished,
         });
+        finished.then(([ok]) => this.props.onFinished(ok));
     };
 
     private onRefreshClick = (): void => {
diff --git a/src/components/views/dialogs/SetEmailDialog.tsx b/src/components/views/dialogs/SetEmailDialog.tsx
index 57d8ed12d4..5628df33ab 100644
--- a/src/components/views/dialogs/SetEmailDialog.tsx
+++ b/src/components/views/dialogs/SetEmailDialog.tsx
@@ -66,12 +66,12 @@ export default class SetEmailDialog extends React.Component<IProps, IState> {
         this.addThreepid = new AddThreepid(MatrixClientPeg.safeGet());
         this.addThreepid.addEmailAddress(emailAddress).then(
             () => {
-                Modal.createDialog(QuestionDialog, {
+                const { finished } = Modal.createDialog(QuestionDialog, {
                     title: _t("auth|set_email|verification_pending_title"),
                     description: _t("auth|set_email|verification_pending_description"),
                     button: _t("action|continue"),
-                    onFinished: this.onEmailDialogFinished,
                 });
+                finished.then(([ok]) => this.onEmailDialogFinished(ok));
             },
             (err) => {
                 this.setState({ emailBusy: false });
@@ -89,7 +89,7 @@ export default class SetEmailDialog extends React.Component<IProps, IState> {
         this.props.onFinished(false);
     };
 
-    private onEmailDialogFinished = (ok: boolean): void => {
+    private onEmailDialogFinished = (ok?: boolean): void => {
         if (ok) {
             this.verifyEmailAddress();
         } else {
@@ -115,12 +115,12 @@ export default class SetEmailDialog extends React.Component<IProps, IState> {
                         _t("settings|general|error_email_verification") +
                         " " +
                         _t("auth|set_email|verification_pending_description");
-                    Modal.createDialog(QuestionDialog, {
+                    const { finished } = Modal.createDialog(QuestionDialog, {
                         title: _t("auth|set_email|verification_pending_title"),
                         description: message,
                         button: _t("action|continue"),
-                        onFinished: this.onEmailDialogFinished,
                     });
+                    finished.then(([ok]) => this.onEmailDialogFinished(ok));
                 } else {
                     logger.error("Unable to verify email address: " + err);
                     Modal.createDialog(ErrorDialog, {
diff --git a/src/components/views/directory/NetworkDropdown.tsx b/src/components/views/directory/NetworkDropdown.tsx
index 82714915cc..e46b89578a 100644
--- a/src/components/views/directory/NetworkDropdown.tsx
+++ b/src/components/views/directory/NetworkDropdown.tsx
@@ -222,10 +222,10 @@ export const NetworkDropdown: React.FC<IProps> = ({ protocols, config, setConfig
                         const [ok, newServer] = await finished;
                         if (!ok) return;
 
-                        if (!allServers.includes(newServer)) {
-                            setUserDefinedServers([...userDefinedServers, newServer]);
+                        if (!allServers.includes(newServer!)) {
+                            setUserDefinedServers([...userDefinedServers, newServer!]);
                             setConfig({
-                                roomServer: newServer,
+                                roomServer: newServer!,
                             });
                         }
                     }}
diff --git a/src/components/views/elements/PollCreateDialog.tsx b/src/components/views/elements/PollCreateDialog.tsx
index 8e23074ca5..41a3bc9dfb 100644
--- a/src/components/views/elements/PollCreateDialog.tsx
+++ b/src/components/views/elements/PollCreateDialog.tsx
@@ -167,18 +167,18 @@ export default class PollCreateDialog extends ScrollableBaseModal<IProps, IState
             .then(() => this.props.onFinished(true))
             .catch((e) => {
                 console.error("Failed to post poll:", e);
-                Modal.createDialog(QuestionDialog, {
+                const { finished } = Modal.createDialog(QuestionDialog, {
                     title: _t("poll|failed_send_poll_title"),
                     description: _t("poll|failed_send_poll_description"),
                     button: _t("action|try_again"),
                     cancelButton: _t("action|cancel"),
-                    onFinished: (tryAgain: boolean) => {
-                        if (!tryAgain) {
-                            this.cancel();
-                        } else {
-                            this.setState({ busy: false, canSubmit: true });
-                        }
-                    },
+                });
+                finished.then(([tryAgain]) => {
+                    if (!tryAgain) {
+                        this.cancel();
+                    } else {
+                        this.setState({ busy: false, canSubmit: true });
+                    }
                 });
             });
     }
diff --git a/src/components/views/elements/ServerPicker.tsx b/src/components/views/elements/ServerPicker.tsx
index 6740534711..430f205377 100644
--- a/src/components/views/elements/ServerPicker.tsx
+++ b/src/components/views/elements/ServerPicker.tsx
@@ -28,9 +28,10 @@ interface IProps {
 const showPickerDialog = (
     title: string | undefined,
     serverConfig: ValidatedServerConfig,
-    onFinished: (config: ValidatedServerConfig) => void,
+    onFinished: (config?: ValidatedServerConfig) => void,
 ): void => {
-    Modal.createDialog(ServerPickerDialog, { title, serverConfig, onFinished });
+    const { finished } = Modal.createDialog(ServerPickerDialog, { title, serverConfig });
+    finished.then(([config]) => onFinished(config));
 };
 
 const onHelpClick = (): void => {
diff --git a/src/components/views/messages/TextualBody.tsx b/src/components/views/messages/TextualBody.tsx
index b51d2fa3f3..d0107b31ec 100644
--- a/src/components/views/messages/TextualBody.tsx
+++ b/src/components/views/messages/TextualBody.tsx
@@ -235,7 +235,7 @@ export default class TextualBody extends React.Component<IBodyProps, IState> {
         scalarClient?.connect().then(() => {
             const completeUrl = scalarClient.getStarterLink(starterLink);
             const integrationsUrl = integrationManager!.uiUrl;
-            Modal.createDialog(QuestionDialog, {
+            const { finished } = Modal.createDialog(QuestionDialog, {
                 title: _t("timeline|scalar_starter_link|dialog_title"),
                 description: (
                     <div>
@@ -243,18 +243,19 @@ export default class TextualBody extends React.Component<IBodyProps, IState> {
                     </div>
                 ),
                 button: _t("action|continue"),
-                onFinished(confirmed) {
-                    if (!confirmed) {
-                        return;
-                    }
-                    const width = window.screen.width > 1024 ? 1024 : window.screen.width;
-                    const height = window.screen.height > 800 ? 800 : window.screen.height;
-                    const left = (window.screen.width - width) / 2;
-                    const top = (window.screen.height - height) / 2;
-                    const features = `height=${height}, width=${width}, top=${top}, left=${left},`;
-                    const wnd = window.open(completeUrl, "_blank", features)!;
-                    wnd.opener = null;
-                },
+            });
+
+            finished.then(([confirmed]) => {
+                if (!confirmed) {
+                    return;
+                }
+                const width = window.screen.width > 1024 ? 1024 : window.screen.width;
+                const height = window.screen.height > 800 ? 800 : window.screen.height;
+                const left = (window.screen.width - width) / 2;
+                const top = (window.screen.height - height) / 2;
+                const features = `height=${height}, width=${width}, top=${top}, left=${left},`;
+                const wnd = window.open(completeUrl, "_blank", features)!;
+                wnd.opener = null;
             });
         });
     };
diff --git a/src/components/views/settings/EventIndexPanel.tsx b/src/components/views/settings/EventIndexPanel.tsx
index 2cfcd70aed..fe19aa0580 100644
--- a/src/components/views/settings/EventIndexPanel.tsx
+++ b/src/components/views/settings/EventIndexPanel.tsx
@@ -119,15 +119,14 @@ export default class EventIndexPanel extends React.Component<EmptyObject, IState
     };
 
     private confirmEventStoreReset = (): void => {
-        const { close } = Modal.createDialog(SeshatResetDialog, {
-            onFinished: async (success): Promise<void> => {
-                if (success) {
-                    await SettingsStore.setValue("enableEventIndexing", null, SettingLevel.DEVICE, false);
-                    await EventIndexPeg.deleteEventIndex();
-                    await this.onEnable();
-                    close();
-                }
-            },
+        const { finished, close } = Modal.createDialog(SeshatResetDialog);
+        finished.then(async ([success]) => {
+            if (success) {
+                await SettingsStore.setValue("enableEventIndexing", null, SettingLevel.DEVICE, false);
+                await EventIndexPeg.deleteEventIndex();
+                await this.onEnable();
+                close();
+            }
         });
     };
 
diff --git a/src/components/views/settings/devices/deleteDevices.tsx b/src/components/views/settings/devices/deleteDevices.tsx
index e2fc6c1abd..894e23e0f7 100644
--- a/src/components/views/settings/devices/deleteDevices.tsx
+++ b/src/components/views/settings/devices/deleteDevices.tsx
@@ -11,7 +11,6 @@ import { type AuthDict, type IAuthData } from "matrix-js-sdk/src/interactive-aut
 
 import { _t } from "../../../../languageHandler";
 import Modal from "../../../../Modal";
-import { type InteractiveAuthCallback } from "../../../structures/InteractiveAuth";
 import { SSOAuthEntry } from "../../auth/InteractiveAuthEntryComponents";
 import InteractiveAuthDialog from "../../dialogs/InteractiveAuthDialog";
 
@@ -24,7 +23,7 @@ const makeDeleteRequest =
 export const deleteDevicesWithInteractiveAuth = async (
     matrixClient: MatrixClient,
     deviceIds: string[],
-    onFinished: InteractiveAuthCallback<void>,
+    onFinished: (success?: boolean) => Promise<void>,
 ): Promise<void> => {
     if (!deviceIds.length) {
         return;
@@ -32,7 +31,7 @@ export const deleteDevicesWithInteractiveAuth = async (
     try {
         await makeDeleteRequest(matrixClient, deviceIds)(null);
         // no interactive auth needed
-        await onFinished(true, undefined);
+        await onFinished(true);
     } catch (error) {
         if (!(error instanceof MatrixError) || error.httpStatus !== 401 || !error.data?.flows) {
             // doesn't look like an interactive-auth failure
@@ -62,16 +61,16 @@ export const deleteDevicesWithInteractiveAuth = async (
                 continueKind: "danger",
             },
         };
-        Modal.createDialog(InteractiveAuthDialog, {
+        const { finished } = Modal.createDialog(InteractiveAuthDialog, {
             title: _t("common|authentication"),
             matrixClient: matrixClient,
             authData: error.data as IAuthData,
-            onFinished,
             makeRequest: makeDeleteRequest(matrixClient, deviceIds),
             aestheticsForStagePhases: {
                 [SSOAuthEntry.LOGIN_TYPE]: dialogAesthetics,
                 [SSOAuthEntry.UNSTABLE_LOGIN_TYPE]: dialogAesthetics,
             },
         });
+        finished.then(([success]) => onFinished(success));
     }
 };
diff --git a/src/components/views/settings/tabs/room/SecurityRoomSettingsTab.tsx b/src/components/views/settings/tabs/room/SecurityRoomSettingsTab.tsx
index a4a94e8bab..89ae96f8a4 100644
--- a/src/components/views/settings/tabs/room/SecurityRoomSettingsTab.tsx
+++ b/src/components/views/settings/tabs/room/SecurityRoomSettingsTab.tsx
@@ -155,7 +155,7 @@ export default class SecurityRoomSettingsTab extends React.Component<IProps, ISt
             if (!confirm) return;
         }
 
-        Modal.createDialog(QuestionDialog, {
+        const { finished } = Modal.createDialog(QuestionDialog, {
             title: _t("room_settings|security|enable_encryption_confirm_title"),
             description: _t(
                 "room_settings|security|enable_encryption_confirm_description",
@@ -164,23 +164,23 @@ export default class SecurityRoomSettingsTab extends React.Component<IProps, ISt
                     a: (sub) => <ExternalLink href={SdkConfig.get("help_encryption_url")}>{sub}</ExternalLink>,
                 },
             ),
-            onFinished: (confirm) => {
-                if (!confirm) {
-                    this.setState({ encrypted: false });
-                    return;
-                }
+        });
+        finished.then(([confirm]) => {
+            if (!confirm) {
+                this.setState({ encrypted: false });
+                return;
+            }
 
-                const beforeEncrypted = this.state.encrypted;
-                this.setState({ encrypted: true });
-                this.context
-                    .sendStateEvent(this.props.room.roomId, EventType.RoomEncryption, {
-                        algorithm: MEGOLM_ENCRYPTION_ALGORITHM,
-                    })
-                    .catch((e) => {
-                        logger.error(e);
-                        this.setState({ encrypted: beforeEncrypted });
-                    });
-            },
+            const beforeEncrypted = this.state.encrypted;
+            this.setState({ encrypted: true });
+            this.context
+                .sendStateEvent(this.props.room.roomId, EventType.RoomEncryption, {
+                    algorithm: MEGOLM_ENCRYPTION_ALGORITHM,
+                })
+                .catch((e) => {
+                    logger.error(e);
+                    this.setState({ encrypted: beforeEncrypted });
+                });
         });
     };
 
@@ -213,9 +213,9 @@ export default class SecurityRoomSettingsTab extends React.Component<IProps, ISt
 
         const [shouldCreate, opts] = await modal.finished;
         if (shouldCreate) {
-            await createRoom(this.context, opts);
+            await createRoom(this.context, opts!);
         }
-        return shouldCreate;
+        return shouldCreate ?? false;
     };
 
     private onHistoryRadioToggle = (history: HistoryVisibility): void => {
diff --git a/src/components/views/settings/tabs/user/AccountUserSettingsTab.tsx b/src/components/views/settings/tabs/user/AccountUserSettingsTab.tsx
index 83c073c3ce..014527f697 100644
--- a/src/components/views/settings/tabs/user/AccountUserSettingsTab.tsx
+++ b/src/components/views/settings/tabs/user/AccountUserSettingsTab.tsx
@@ -165,10 +165,9 @@ const AccountUserSettingsTab: React.FC<IProps> = ({ closeSettingsFn }) => {
     }, []);
 
     const onDeactivateClicked = useCallback((): void => {
-        Modal.createDialog(DeactivateAccountDialog, {
-            onFinished: (success) => {
-                if (success) closeSettingsFn();
-            },
+        const { finished } = Modal.createDialog(DeactivateAccountDialog);
+        finished.then(([success]) => {
+            if (success) closeSettingsFn();
         });
     }, [closeSettingsFn]);
 
diff --git a/src/components/views/settings/tabs/user/EncryptionUserSettingsTab.tsx b/src/components/views/settings/tabs/user/EncryptionUserSettingsTab.tsx
index 2303a1e50c..dea28628fb 100644
--- a/src/components/views/settings/tabs/user/EncryptionUserSettingsTab.tsx
+++ b/src/components/views/settings/tabs/user/EncryptionUserSettingsTab.tsx
@@ -247,7 +247,10 @@ function SetUpEncryptionPanel({ onFinish }: SetUpEncryptionPanelProps): JSX.Elem
             <Button
                 size="sm"
                 Icon={ComputerIcon}
-                onClick={() => Modal.createDialog(SetupEncryptionDialog, { onFinished: onFinish })}
+                onClick={() => {
+                    const { finished } = Modal.createDialog(SetupEncryptionDialog);
+                    finished.then(onFinish);
+                }}
             >
                 {_t("settings|encryption|device_not_verified_button")}
             </Button>
diff --git a/src/components/views/settings/tabs/user/SessionManagerTab.tsx b/src/components/views/settings/tabs/user/SessionManagerTab.tsx
index c5d9385d7b..262f788daa 100644
--- a/src/components/views/settings/tabs/user/SessionManagerTab.tsx
+++ b/src/components/views/settings/tabs/user/SessionManagerTab.tsx
@@ -100,7 +100,7 @@ const useSignOut = (
             } else {
                 const deferredSuccess = defer<boolean>();
                 await deleteDevicesWithInteractiveAuth(matrixClient, deviceIds, async (success) => {
-                    deferredSuccess.resolve(success);
+                    deferredSuccess.resolve(!!success);
                 });
                 success = await deferredSuccess.promise;
             }
@@ -203,7 +203,8 @@ const SessionManagerTab: React.FC<{
     const shouldShowOtherSessions = otherSessionsCount > 0;
 
     const onVerifyCurrentDevice = (): void => {
-        Modal.createDialog(SetupEncryptionDialog, { onFinished: refreshDevices });
+        const { finished } = Modal.createDialog(SetupEncryptionDialog);
+        finished.then(refreshDevices);
     };
 
     const onTriggerDeviceVerification = useCallback(
@@ -212,14 +213,14 @@ const SessionManagerTab: React.FC<{
                 return;
             }
             const verificationRequestPromise = requestDeviceVerification(deviceId);
-            Modal.createDialog(VerificationRequestDialog, {
+            const { finished } = Modal.createDialog(VerificationRequestDialog, {
                 verificationRequestPromise,
                 member: currentUserMember,
-                onFinished: async (): Promise<void> => {
-                    const request = await verificationRequestPromise;
-                    request.cancel();
-                    await refreshDevices();
-                },
+            });
+            finished.then(async () => {
+                const request = await verificationRequestPromise;
+                request.cancel();
+                await refreshDevices();
             });
         },
         [requestDeviceVerification, refreshDevices, currentUserMember],
diff --git a/src/components/views/toasts/VerificationRequestToast.tsx b/src/components/views/toasts/VerificationRequestToast.tsx
index e3975c148b..12843c0b87 100644
--- a/src/components/views/toasts/VerificationRequestToast.tsx
+++ b/src/components/views/toasts/VerificationRequestToast.tsx
@@ -124,18 +124,16 @@ export default class VerificationRequestToast extends React.PureComponent<IProps
                     request.roomId,
                 );
             } else {
-                Modal.createDialog(
+                const { finished } = Modal.createDialog(
                     VerificationRequestDialog,
                     {
                         verificationRequest: request,
-                        onFinished: () => {
-                            request.cancel();
-                        },
                     },
                     undefined,
                     /* priority = */ false,
                     /* static = */ true,
                 );
+                finished.then(() => request.cancel());
             }
             await request.accept();
         } catch (err) {
diff --git a/src/slash-commands/utils.ts b/src/slash-commands/utils.ts
index f1be124151..d9cf15d16a 100644
--- a/src/slash-commands/utils.ts
+++ b/src/slash-commands/utils.ts
@@ -49,16 +49,14 @@ export const singleMxcUpload = async (cli: MatrixClient): Promise<string | null>
             const file = (ev as HTMLInputEvent).target.files?.[0];
             if (!file) return;
 
-            Modal.createDialog(UploadConfirmDialog, {
-                file,
-                onFinished: async (shouldContinue): Promise<void> => {
-                    if (shouldContinue) {
-                        const { content_uri: uri } = await cli.uploadContent(file);
-                        resolve(uri);
-                    } else {
-                        resolve(null);
-                    }
-                },
+            const { finished } = Modal.createDialog(UploadConfirmDialog, { file });
+            finished.then(async ([shouldContinue]) => {
+                if (shouldContinue) {
+                    const { content_uri: uri } = await cli.uploadContent(file);
+                    resolve(uri);
+                } else {
+                    resolve(null);
+                }
             });
         };
 
diff --git a/src/stores/ModalWidgetStore.ts b/src/stores/ModalWidgetStore.ts
index 10f16d24d2..2a2fbdd8da 100644
--- a/src/stores/ModalWidgetStore.ts
+++ b/src/stores/ModalWidgetStore.ts
@@ -61,18 +61,18 @@ export class ModalWidgetStore extends AsyncStoreWithClient<IState> {
                 widgetDefinition: { ...requestData },
                 widgetRoomId,
                 sourceWidgetId: sourceWidget.id,
-                onFinished: (success, data) => {
-                    this.closeModalWidget(sourceWidget, widgetRoomId, success && data ? data : { "m.exited": true });
-
-                    this.openSourceWidgetId = null;
-                    this.openSourceWidgetRoomId = null;
-                    this.modalInstance = null;
-                },
             },
             undefined,
             /* priority = */ false,
             /* static = */ true,
         );
+        this.modalInstance!.finished.then(([success, data]) => {
+            this.closeModalWidget(sourceWidget, widgetRoomId, success && data ? data : { "m.exited": true });
+
+            this.openSourceWidgetId = null;
+            this.openSourceWidgetRoomId = null;
+            this.modalInstance = null;
+        });
     };
 
     public closeModalWidget = (
diff --git a/src/stores/widgets/StopGapWidgetDriver.ts b/src/stores/widgets/StopGapWidgetDriver.ts
index 31d1d6edac..e0bc85746f 100644
--- a/src/stores/widgets/StopGapWidgetDriver.ts
+++ b/src/stores/widgets/StopGapWidgetDriver.ts
@@ -557,19 +557,17 @@ export class StopGapWidgetDriver extends WidgetDriver {
 
         observer.update({ state: OpenIDRequestState.PendingUserConfirmation });
 
-        Modal.createDialog(WidgetOpenIDPermissionsDialog, {
+        const { finished } = Modal.createDialog(WidgetOpenIDPermissionsDialog, {
             widget: this.forWidget,
             widgetKind: this.forWidgetKind,
             inRoomId: this.inRoomId,
-
-            onFinished: async (confirm): Promise<void> => {
-                if (!confirm) {
-                    return observer.update({ state: OpenIDRequestState.Blocked });
-                }
-
-                return observer.update({ state: OpenIDRequestState.Allowed, token: await getToken() });
-            },
         });
+        const [confirm] = await finished;
+        if (!confirm) {
+            observer.update({ state: OpenIDRequestState.Blocked });
+        } else {
+            observer.update({ state: OpenIDRequestState.Allowed, token: await getToken() });
+        }
     }
 
     public async navigate(uri: string): Promise<void> {
diff --git a/src/toasts/AnalyticsToast.tsx b/src/toasts/AnalyticsToast.tsx
index 63e0757520..351ccdf4b2 100644
--- a/src/toasts/AnalyticsToast.tsx
+++ b/src/toasts/AnalyticsToast.tsx
@@ -34,34 +34,36 @@ const onReject = (): void => {
 };
 
 const onLearnMoreNoOptIn = (): void => {
-    showAnalyticsLearnMoreDialog({
-        onFinished: (buttonClicked?: ButtonClicked) => {
-            if (buttonClicked === ButtonClicked.Primary) {
-                // user clicked "Enable"
-                onAccept();
-            }
-            // otherwise, the user either clicked "Cancel", or closed the dialog without making a choice,
-            // leave the toast open
-        },
+    const { finished } = showAnalyticsLearnMoreDialog({
         primaryButton: _t("action|enable"),
     });
+
+    finished.then(([buttonClicked]) => {
+        if (buttonClicked === ButtonClicked.Primary) {
+            // user clicked "Enable"
+            onAccept();
+        }
+        // otherwise, the user either clicked "Cancel", or closed the dialog without making a choice,
+        // leave the toast open
+    });
 };
 
 const onLearnMorePreviouslyOptedIn = (): void => {
-    showAnalyticsLearnMoreDialog({
-        onFinished: (buttonClicked?: ButtonClicked) => {
-            if (buttonClicked === ButtonClicked.Primary) {
-                // user clicked "That's fine"
-                onAccept();
-            } else if (buttonClicked === ButtonClicked.Cancel) {
-                // user clicked "Stop"
-                onReject();
-            }
-            // otherwise, the user closed the dialog without making a choice, leave the toast open
-        },
+    const { finished } = showAnalyticsLearnMoreDialog({
         primaryButton: _t("analytics|accept_button"),
         cancelButton: _t("action|stop"),
     });
+
+    finished.then(([buttonClicked]) => {
+        if (buttonClicked === ButtonClicked.Primary) {
+            // user clicked "That's fine"
+            onAccept();
+        } else if (buttonClicked === ButtonClicked.Cancel) {
+            // user clicked "Stop"
+            onReject();
+        }
+        // otherwise, the user closed the dialog without making a choice, leave the toast open
+    });
 };
 
 const TOAST_KEY = "analytics";
diff --git a/src/toasts/UpdateToast.tsx b/src/toasts/UpdateToast.tsx
index 0abc95c066..4ced8144c1 100644
--- a/src/toasts/UpdateToast.tsx
+++ b/src/toasts/UpdateToast.tsx
@@ -32,27 +32,27 @@ export const showToast = (version: string, newVersion: string, releaseNotes?: st
     let acceptLabel = _t("update|see_changes_button");
     if (releaseNotes) {
         onAccept = () => {
-            Modal.createDialog(QuestionDialog, {
+            const { finished } = Modal.createDialog(QuestionDialog, {
                 title: _t("update|release_notes_toast_title"),
                 description: <pre>{releaseNotes}</pre>,
                 button: _t("action|update"),
-                onFinished: (update) => {
-                    if (update && PlatformPeg.get()) {
-                        PlatformPeg.get()!.installUpdate();
-                    }
-                },
+            });
+            finished.then(([update]) => {
+                if (update && PlatformPeg.get()) {
+                    PlatformPeg.get()!.installUpdate();
+                }
             });
         };
     } else if (checkVersion(version) && checkVersion(newVersion)) {
         onAccept = () => {
-            Modal.createDialog(ChangelogDialog, {
+            const { finished } = Modal.createDialog(ChangelogDialog, {
                 version,
                 newVersion,
-                onFinished: (update) => {
-                    if (update && PlatformPeg.get()) {
-                        PlatformPeg.get()!.installUpdate();
-                    }
-                },
+            });
+            finished.then(([update]) => {
+                if (update && PlatformPeg.get()) {
+                    PlatformPeg.get()!.installUpdate();
+                }
             });
         };
     } else {
diff --git a/src/utils/DialogOpener.ts b/src/utils/DialogOpener.ts
index 8304d6c2aa..9eadf63adf 100644
--- a/src/utils/DialogOpener.ts
+++ b/src/utils/DialogOpener.ts
@@ -119,7 +119,7 @@ export class DialogOpener {
                 break;
             case Action.OpenAddToExistingSpaceDialog: {
                 const space = payload.space;
-                Modal.createDialog(
+                const { finished } = Modal.createDialog(
                     AddExistingToSpaceDialog,
                     {
                         onCreateRoomClick: (ev: ButtonEvent) => {
@@ -128,14 +128,14 @@ export class DialogOpener {
                         },
                         onAddSubspaceClick: () => showAddExistingSubspace(space),
                         space,
-                        onFinished: (added: boolean) => {
-                            if (added && SdkContextClass.instance.roomViewStore.getRoomId() === space.roomId) {
-                                defaultDispatcher.fire(Action.UpdateSpaceHierarchy);
-                            }
-                        },
                     },
                     "mx_AddExistingToSpaceDialog_wrapper",
                 );
+                finished.then(([added]) => {
+                    if (added && SdkContextClass.instance.roomViewStore.getRoomId() === space.roomId) {
+                        defaultDispatcher.fire(Action.UpdateSpaceHierarchy);
+                    }
+                });
                 break;
             }
         }
diff --git a/src/utils/leave-behaviour.ts b/src/utils/leave-behaviour.ts
index ec24903ad4..2ad6e7d4fe 100644
--- a/src/utils/leave-behaviour.ts
+++ b/src/utils/leave-behaviour.ts
@@ -171,20 +171,20 @@ export async function leaveRoomBehaviour(
 }
 
 export const leaveSpace = (space: Room): void => {
-    Modal.createDialog(
+    const { finished } = Modal.createDialog(
         LeaveSpaceDialog,
         {
             space,
-            onFinished: async (leave: boolean, rooms: Room[]): Promise<void> => {
-                if (!leave) return;
-                await bulkSpaceBehaviour(space, rooms, (room) => leaveRoomBehaviour(space.client, room.roomId));
-
-                dis.dispatch<AfterLeaveRoomPayload>({
-                    action: Action.AfterLeaveRoom,
-                    room_id: space.roomId,
-                });
-            },
         },
         "mx_LeaveSpaceDialog_wrapper",
     );
+    finished.then(async ([leave, rooms]) => {
+        if (!leave) return;
+        await bulkSpaceBehaviour(space, rooms!, (room) => leaveRoomBehaviour(space.client, room.roomId));
+
+        dis.dispatch<AfterLeaveRoomPayload>({
+            action: Action.AfterLeaveRoom,
+            room_id: space.roomId,
+        });
+    });
 };
diff --git a/src/utils/space.tsx b/src/utils/space.tsx
index 1a9b104c4b..230c783322 100644
--- a/src/utils/space.tsx
+++ b/src/utils/space.tsx
@@ -75,7 +75,7 @@ export const showCreateNewRoom = async (space: Room, type?: RoomType): Promise<b
     });
     const [shouldCreate, opts] = await modal.finished;
     if (shouldCreate) {
-        await createRoom(space.client, opts);
+        await createRoom(space.client, opts!);
     }
     return !!shouldCreate;
 };
@@ -106,35 +106,35 @@ export const showSpaceInvite = (space: Room, initialText = ""): void => {
 };
 
 export const showAddExistingSubspace = (space: Room): void => {
-    Modal.createDialog(
+    const { finished } = Modal.createDialog(
         AddExistingSubspaceDialog,
         {
             space,
             onCreateSubspaceClick: () => showCreateNewSubspace(space),
-            onFinished: (added: boolean) => {
-                if (added && SdkContextClass.instance.roomViewStore.getRoomId() === space.roomId) {
-                    defaultDispatcher.fire(Action.UpdateSpaceHierarchy);
-                }
-            },
         },
         "mx_AddExistingToSpaceDialog_wrapper",
     );
+    finished.then(([added]) => {
+        if (added && SdkContextClass.instance.roomViewStore.getRoomId() === space.roomId) {
+            defaultDispatcher.fire(Action.UpdateSpaceHierarchy);
+        }
+    });
 };
 
 export const showCreateNewSubspace = (space: Room): void => {
-    Modal.createDialog(
+    const { finished } = Modal.createDialog(
         CreateSubspaceDialog,
         {
             space,
             onAddExistingSpaceClick: () => showAddExistingSubspace(space),
-            onFinished: (added: boolean) => {
-                if (added && SdkContextClass.instance.roomViewStore.getRoomId() === space.roomId) {
-                    defaultDispatcher.fire(Action.UpdateSpaceHierarchy);
-                }
-            },
         },
         "mx_CreateSubspaceDialog_wrapper",
     );
+    finished.then(([added]) => {
+        if (added && SdkContextClass.instance.roomViewStore.getRoomId() === space.roomId) {
+            defaultDispatcher.fire(Action.UpdateSpaceHierarchy);
+        }
+    });
 };
 
 export const bulkSpaceBehaviour = async (
diff --git a/test/unit-tests/Modal-test.ts b/test/unit-tests/Modal-test.ts
index d542fa3843..121c027b01 100644
--- a/test/unit-tests/Modal-test.ts
+++ b/test/unit-tests/Modal-test.ts
@@ -9,6 +9,7 @@ Please see LICENSE files in the repository root for full details.
 import Modal from "../../src/Modal";
 import QuestionDialog from "../../src/components/views/dialogs/QuestionDialog";
 import defaultDispatcher from "../../src/dispatcher/dispatcher";
+import { flushPromises } from "../test-utils";
 
 describe("Modal", () => {
     test("forceCloseAllModals should close all open modals", () => {
@@ -23,7 +24,7 @@ describe("Modal", () => {
         expect(Modal.hasDialogs()).toBe(false);
     });
 
-    test("open modals should be closed on logout", () => {
+    test("open modals should be closed on logout", async () => {
         const modal1OnFinished = jest.fn();
         const modal2OnFinished = jest.fn();
 
@@ -31,18 +32,18 @@ describe("Modal", () => {
             title: "Test dialog 1",
             description: "This is a test dialog",
             button: "Word",
-            onFinished: modal1OnFinished,
-        });
+        }).finished.then(modal1OnFinished);
 
         Modal.createDialog(QuestionDialog, {
             title: "Test dialog 2",
             description: "This is a test dialog",
             button: "Word",
-            onFinished: modal2OnFinished,
-        });
+        }).finished.then(modal2OnFinished);
 
         defaultDispatcher.dispatch({ action: "logout" }, true);
 
+        await flushPromises();
+
         expect(modal1OnFinished).toHaveBeenCalled();
         expect(modal2OnFinished).toHaveBeenCalled();
     });
diff --git a/test/unit-tests/components/views/settings/devices/deleteDevices-test.tsx b/test/unit-tests/components/views/settings/devices/deleteDevices-test.tsx
index 3b030c61c9..603d06d4a6 100644
--- a/test/unit-tests/components/views/settings/devices/deleteDevices-test.tsx
+++ b/test/unit-tests/components/views/settings/devices/deleteDevices-test.tsx
@@ -35,7 +35,7 @@ describe("deleteDevices()", () => {
         await deleteDevicesWithInteractiveAuth(mockClient, deviceIds, onFinished);
 
         expect(mockClient.deleteMultipleDevices).toHaveBeenCalledWith(deviceIds, undefined);
-        expect(onFinished).toHaveBeenCalledWith(true, undefined);
+        expect(onFinished).toHaveBeenCalledWith(true);
 
         // didnt open modal
         expect(modalSpy).not.toHaveBeenCalled();
diff --git a/test/unit-tests/components/views/settings/tabs/user/AccountUserSettingsTab-test.tsx b/test/unit-tests/components/views/settings/tabs/user/AccountUserSettingsTab-test.tsx
index f6b6b2e850..531e66e00b 100644
--- a/test/unit-tests/components/views/settings/tabs/user/AccountUserSettingsTab-test.tsx
+++ b/test/unit-tests/components/views/settings/tabs/user/AccountUserSettingsTab-test.tsx
@@ -9,6 +9,7 @@ Please see LICENSE files in the repository root for full details.
 import { fireEvent, render, screen, within } from "jest-matrix-react";
 import React from "react";
 import { type MatrixClient, ThreepidMedium } from "matrix-js-sdk/src/matrix";
+import { defer } from "matrix-js-sdk/src/utils";
 import { logger } from "matrix-js-sdk/src/logger";
 import userEvent from "@testing-library/user-event";
 import { type MockedObject } from "jest-mock";
@@ -153,7 +154,8 @@ describe("<AccountUserSettingsTab />", () => {
                 (settingName) => settingName === UIFeature.Deactivate,
             );
 
-            const createDialogFn = jest.fn();
+            const finishedDeferred = defer<[boolean]>();
+            const createDialogFn = jest.fn().mockReturnValue({ finished: finishedDeferred.promise });
             jest.spyOn(Modal, "createDialog").mockImplementation(createDialogFn);
 
             render(getComponent());
@@ -167,14 +169,16 @@ describe("<AccountUserSettingsTab />", () => {
                 (settingName) => settingName === UIFeature.Deactivate,
             );
 
-            const createDialogFn = jest.fn();
+            const finishedDeferred = defer<[boolean]>();
+            const createDialogFn = jest.fn().mockReturnValue({ finished: finishedDeferred.promise });
             jest.spyOn(Modal, "createDialog").mockImplementation(createDialogFn);
 
             render(getComponent());
 
             await userEvent.click(screen.getByRole("button", { name: "Deactivate Account" }));
 
-            createDialogFn.mock.calls[0][1].onFinished(true);
+            finishedDeferred.resolve([true]);
+            await flushPromises();
 
             expect(defaultProps.closeSettingsFn).toHaveBeenCalled();
         });
@@ -183,14 +187,16 @@ describe("<AccountUserSettingsTab />", () => {
                 (settingName) => settingName === UIFeature.Deactivate,
             );
 
-            const createDialogFn = jest.fn();
+            const finishedDeferred = defer<[boolean]>();
+            const createDialogFn = jest.fn().mockReturnValue({ finished: finishedDeferred.promise });
             jest.spyOn(Modal, "createDialog").mockImplementation(createDialogFn);
 
             render(getComponent());
 
             await userEvent.click(screen.getByRole("button", { name: "Deactivate Account" }));
 
-            createDialogFn.mock.calls[0][1].onFinished(false);
+            finishedDeferred.resolve([false]);
+            await flushPromises();
 
             expect(defaultProps.closeSettingsFn).not.toHaveBeenCalled();
         });
diff --git a/test/unit-tests/components/views/settings/tabs/user/EncryptionUserSettingsTab-test.tsx b/test/unit-tests/components/views/settings/tabs/user/EncryptionUserSettingsTab-test.tsx
index 584a1b3c8c..018ec25ef3 100644
--- a/test/unit-tests/components/views/settings/tabs/user/EncryptionUserSettingsTab-test.tsx
+++ b/test/unit-tests/components/views/settings/tabs/user/EncryptionUserSettingsTab-test.tsx
@@ -62,7 +62,7 @@ describe("<EncryptionUserSettingsTab />", () => {
         );
         expect(asFragment()).toMatchSnapshot();
 
-        const spy = jest.spyOn(Modal, "createDialog").mockReturnValue({} as any);
+        const spy = jest.spyOn(Modal, "createDialog").mockReturnValue({ finished: new Promise(() => {}) } as any);
         await user.click(screen.getByText("Verify this device"));
         expect(spy).toHaveBeenCalled();
     });
diff --git a/test/unit-tests/components/views/settings/tabs/user/SessionManagerTab-test.tsx b/test/unit-tests/components/views/settings/tabs/user/SessionManagerTab-test.tsx
index eaae755382..2dcc6d1cd6 100644
--- a/test/unit-tests/components/views/settings/tabs/user/SessionManagerTab-test.tsx
+++ b/test/unit-tests/components/views/settings/tabs/user/SessionManagerTab-test.tsx
@@ -631,9 +631,10 @@ describe("<SessionManagerTab />", () => {
             // click verify button from current session section
             fireEvent.click(getByTestId(`verification-status-button-${alicesMobileDevice.device_id}`));
 
-            const { onFinished: modalOnFinished } = modalSpy.mock.calls[0][1] as any;
-            // simulate modal completing process
-            await modalOnFinished();
+            // close the modal
+            const { close: closeModal } = modalSpy.mock.results[0].value;
+            closeModal();
+            await flushPromises();
 
             // cancelled in case it was a failure exit from modal
             expect(mockVerificationRequest.cancel).toHaveBeenCalled();