diff --git a/app/controllers/plugins_controller.rb b/app/controllers/plugins_controller.rb
index a766832..c7210ea 100644
--- a/app/controllers/plugins_controller.rb
+++ b/app/controllers/plugins_controller.rb
@@ -30,9 +30,15 @@ class PluginsController < ApplicationController
   end
 
   def upgrade
-    pl = Plugin.new(gem_name: params[:plugins][:name])
-    pl.uninstall! if pl.installed?
     GemInstaller.new.async.perform(params[:plugins][:name], params[:plugins][:version])
     redirect_to plugins_path
   end
+
+  def bulk_upgrade
+    params[:plugins].each do |gem_name|
+      pl = Plugin.new(gem_name: gem_name)
+      GemInstaller.new.async.perform(gem_name, pl.latest_version)
+    end
+    redirect_to plugins_path
+  end
 end
diff --git a/app/models/plugin.rb b/app/models/plugin.rb
index a87a499..5a1de99 100644
--- a/app/models/plugin.rb
+++ b/app/models/plugin.rb
@@ -78,7 +78,7 @@ class Plugin
 
   def inspect
     self.version ||= latest_version
-    %Q|<"#{gem_name}", "#{version}">|
+    %Q|<#{gem_name}, "#{version}">|
   end
 
   def rubygems_org_page
@@ -88,9 +88,12 @@ class Plugin
   def self.installed
     Rails.cache.fetch("installed_gems", expires_in: 3.seconds) do
       Bundler.with_clean_env do
-        `#{fluent_gem_path} list`.lines.grep(/fluent-plugin/).map do |gem|
-          name, version = gem.strip.split(" (")
-          new(gem_name: name, version: version.gsub(/\)$/, ""))
+        gems = `#{fluent_gem_path} list`.try(:lines)
+        return [] unless gems
+        gems.grep(/fluent-plugin/).map do |gem|
+          name, versions_str = gem.strip.split(" ")
+          version = versions_str[/[^(), ]+/]
+          new(gem_name: name, version: version)
         end
       end
     end
diff --git a/app/views/plugins/updated.html.haml b/app/views/plugins/updated.html.haml
index 66288e7..0eba8a1 100644
--- a/app/views/plugins/updated.html.haml
+++ b/app/views/plugins/updated.html.haml
@@ -3,7 +3,7 @@
 - unless @plugins.present?
   = t('.no_updates')
 - else
-  = form_tag(install_plugins_path, method: :patch) do
+  = form_tag(bulk_upgrade_plugins_path, method: :patch) do
     %table{class: "table table-striped table-hover"}
       %tr
         %th.col-lg-2= t('.name')
diff --git a/config/routes.rb b/config/routes.rb
index c94d097..a572596 100644
--- a/config/routes.rb
+++ b/config/routes.rb
@@ -55,6 +55,7 @@ Rails.application.routes.draw do
       patch :install
       patch :uninstall
       patch :upgrade
+      patch :bulk_upgrade
     end
   end