diff --git a/include/proto/connection.h b/include/proto/connection.h
index 7c969eb4c..af995cd15 100644
--- a/include/proto/connection.h
+++ b/include/proto/connection.h
@@ -601,6 +601,18 @@ static inline const char *conn_err_code_str(struct connection *c)
 {
 	switch (c->err_code) {
 	case CO_ER_NONE:          return "Success";
+
+	case CO_ER_CONF_FDLIM:    return "Reached configured maxconn value";
+	case CO_ER_PROC_FDLIM:    return "Too many sockets on the process";
+	case CO_ER_SYS_FDLIM:     return "Too many sockets on the system";
+	case CO_ER_SYS_MEMLIM:    return "Out of system buffers";
+	case CO_ER_NOPROTO:       return "Protocol or address family not supported";
+	case CO_ER_SOCK_ERR:      return "General socket error";
+	case CO_ER_PORT_RANGE:    return "Source port range exhausted";
+	case CO_ER_CANT_BIND:     return "Can't bind to source address";
+	case CO_ER_FREE_PORTS:    return "Out of local source ports on the system";
+	case CO_ER_ADDR_INUSE:    return "Local source address already in use";
+
 	case CO_ER_PRX_EMPTY:     return "Connection closed while waiting for PROXY protocol header";
 	case CO_ER_PRX_ABORT:     return "Connection error while waiting for PROXY protocol header";
 	case CO_ER_PRX_TIMEOUT:   return "Timeout while waiting for PROXY protocol header";
diff --git a/include/types/connection.h b/include/types/connection.h
index eb99cc9ac..cf93999e0 100644
--- a/include/types/connection.h
+++ b/include/types/connection.h
@@ -149,6 +149,19 @@ enum {
 /* possible connection error codes */
 enum {
 	CO_ER_NONE,             /* no error */
+
+	CO_ER_CONF_FDLIM,       /* reached process' configured FD limitation */
+	CO_ER_PROC_FDLIM,       /* reached process' FD limitation */
+	CO_ER_SYS_FDLIM,        /* reached system's FD limitation */
+	CO_ER_SYS_MEMLIM,       /* reached system buffers limitation */
+	CO_ER_NOPROTO,          /* protocol not supported */
+	CO_ER_SOCK_ERR,         /* other socket error */
+
+	CO_ER_PORT_RANGE,       /* source port range exhausted */
+	CO_ER_CANT_BIND,        /* can't bind to source address */
+	CO_ER_FREE_PORTS,       /* no more free ports on the system */
+	CO_ER_ADDR_INUSE,       /* local address already in use */
+
 	CO_ER_PRX_EMPTY,        /* nothing received in PROXY protocol header */
 	CO_ER_PRX_ABORT,        /* client abort during PROXY protocol header */
 	CO_ER_PRX_TIMEOUT,      /* timeout while waiting for a PROXY header */