diff --git a/src/main/scala/gitbucket/core/controller/AccountController.scala b/src/main/scala/gitbucket/core/controller/AccountController.scala
index da07cde..caea806 100644
--- a/src/main/scala/gitbucket/core/controller/AccountController.scala
+++ b/src/main/scala/gitbucket/core/controller/AccountController.scala
@@ -347,7 +347,7 @@
 
         updateImage(userName, form.fileId, form.clearImage)
         updateAccountExtraMailAddresses(userName, form.extraMailAddresses.filter(_ != ""))
-        flash += "info" -> "Account information has been updated."
+        flash.update("info", "Account information has been updated.")
         redirect(s"/${userName}/_edit")
 
     } getOrElse NotFound()
@@ -359,7 +359,7 @@
     getAccountByUserName(userName, true).map {
       account =>
         if (isLastAdministrator(account)) {
-          flash += "error" -> "Account can't be removed because this is last one administrator."
+          flash.update("error", "Account can't be removed because this is last one administrator.")
           redirect(s"/${userName}/_edit")
         } else {
 //      // Remove repositories
@@ -439,7 +439,7 @@
     val userName = params("userName")
     getAccountByUserName(userName).map { x =>
       val (tokenId, token) = generateAccessToken(userName, form.note)
-      flash += "generatedToken" -> (tokenId, token)
+      flash.update("generatedToken", (tokenId, token))
     }
     redirect(s"/${userName}/_application")
   })
@@ -475,7 +475,7 @@
   post("/:userName/_hooks/new", accountWebHookForm(false))(managersOnly { form =>
     val userName = params("userName")
     addAccountWebHook(userName, form.url, form.events, form.ctype, form.token)
-    flash += "info" -> s"Webhook ${form.url} created"
+    flash.update("info", s"Webhook ${form.url} created")
     redirect(s"/${userName}/_hooks")
   })
 
@@ -485,7 +485,7 @@
   get("/:userName/_hooks/delete")(managersOnly {
     val userName = params("userName")
     deleteAccountWebHook(userName, params("url"))
-    flash += "info" -> s"Webhook ${params("url")} deleted"
+    flash.update("info", s"Webhook ${params("url")} deleted")
     redirect(s"/${userName}/_hooks")
   })
 
@@ -508,7 +508,7 @@
   post("/:userName/_hooks/edit", accountWebHookForm(true))(managersOnly { form =>
     val userName = params("userName")
     updateAccountWebHook(userName, form.url, form.events, form.ctype, form.token)
-    flash += "info" -> s"webhook ${form.url} updated"
+    flash.update("info", s"webhook ${form.url} updated")
     redirect(s"/${userName}/_hooks")
   })
 
@@ -683,7 +683,7 @@
 
           updateImage(form.groupName, form.fileId, form.clearImage)
 
-          flash += "info" -> "Account information has been updated."
+          flash.update("info", "Account information has been updated.")
           redirect(s"/${groupName}/_editgroup")
 
         } getOrElse NotFound()
diff --git a/src/main/scala/gitbucket/core/controller/IndexController.scala b/src/main/scala/gitbucket/core/controller/IndexController.scala
index df74ac8..dd80b47 100644
--- a/src/main/scala/gitbucket/core/controller/IndexController.scala
+++ b/src/main/scala/gitbucket/core/controller/IndexController.scala
@@ -83,7 +83,7 @@
   get("/signin") {
     val redirect = params.get("redirect")
     if (redirect.isDefined && redirect.get.startsWith("/")) {
-      flash += Keys.Flash.Redirect -> redirect.get
+      flash.update(Keys.Flash.Redirect, redirect.get)
     }
     gitbucket.core.html.signin(flash.get("userName"), flash.get("password"), flash.get("error"))
   }
@@ -96,9 +96,9 @@
           case _                         => signin(account)
         }
       case None =>
-        flash += "userName" -> form.userName
-        flash += "password" -> form.password
-        flash += "error" -> "Sorry, your Username and/or Password is incorrect. Please try again."
+        flash.update("userName", form.userName)
+        flash.update("password", form.password)
+        flash.update("error", "Sorry, your Username and/or Password is incorrect. Please try again.")
         redirect("/signin")
     }
   }
@@ -135,12 +135,12 @@
           authenticate(params.toMap, redirectURI, context.state, context.nonce, oidc).map { account =>
             signin(account, context.redirectBackURI)
           } orElse {
-            flash += "error" -> "Sorry, authentication failed. Please try again."
+            flash.update("error", "Sorry, authentication failed. Please try again.")
             session.invalidate()
             redirect("/signin")
           }
         case _ =>
-          flash += "error" -> "Sorry, something wrong. Please try again."
+          flash.update("error", "Sorry, something wrong. Please try again.")
           session.invalidate()
           redirect("/signin")
       }
@@ -227,7 +227,7 @@
     } getOrElse ""
   })
 
-  // TODO Move to RepositoryViwerController?
+  // TODO Move to RepositoryViewrController?
   get("/:owner/:repository/search")(referrersOnly { repository =>
     defining(params.getOrElse("q", "").trim, params.getOrElse("type", "code")) {
       case (query, target) =>
diff --git a/src/main/scala/gitbucket/core/controller/PullRequestsController.scala b/src/main/scala/gitbucket/core/controller/PullRequestsController.scala
index 50523c8..2eae306 100644
--- a/src/main/scala/gitbucket/core/controller/PullRequestsController.scala
+++ b/src/main/scala/gitbucket/core/controller/PullRequestsController.scala
@@ -269,7 +269,7 @@
       val repository = getRepository(owner, name).get
       val branchProtection = getProtectedBranchInfo(owner, name, pullreq.requestBranch)
       if (branchProtection.enabled) {
-        flash += "error" -> s"branch ${pullreq.requestBranch} is protected."
+        flash.update("error", s"branch ${pullreq.requestBranch} is protected.")
       } else {
         if (repository.repository.defaultBranch != pullreq.requestBranch) {
           val userName = context.loginAccount.get.userName
@@ -286,7 +286,7 @@
             "delete_branch"
           )
         } else {
-          flash += "error" -> s"""Can't delete the default branch "${pullreq.requestBranch}"."""
+          flash.update("error", s"""Can't delete the default branch "${pullreq.requestBranch}".""")
         }
       }
 
@@ -307,7 +307,7 @@
     } yield {
       val branchProtection = getProtectedBranchInfo(owner, name, pullreq.requestBranch)
       if (branchProtection.needStatusCheck(loginAccount.userName)) {
-        flash += "error" -> s"branch ${pullreq.requestBranch} is protected need status check."
+        flash.update("error", s"branch ${pullreq.requestBranch} is protected need status check.")
       } else {
         LockUtil.lock(s"${owner}/${name}") {
           val alias =
@@ -329,11 +329,11 @@
             Some(pullreq)
           ) match {
             case None => // conflict
-              flash += "error" -> s"Can't automatic merging branch '${alias}' into ${pullreq.requestBranch}."
+              flash.update("error", s"Can't automatic merging branch '${alias}' into ${pullreq.requestBranch}.")
             case Some(oldId) =>
               // update pull request
               updatePullRequests(owner, name, pullreq.requestBranch, loginAccount, "synchronize")
-              flash += "info" -> s"Merge branch '${alias}' into ${pullreq.requestBranch}"
+              flash.update("info", s"Merge branch '${alias}' into ${pullreq.requestBranch}")
           }
         }
       }
diff --git a/src/main/scala/gitbucket/core/controller/RepositorySettingsController.scala b/src/main/scala/gitbucket/core/controller/RepositorySettingsController.scala
index 4dc1dc0..e98f2c1 100644
--- a/src/main/scala/gitbucket/core/controller/RepositorySettingsController.scala
+++ b/src/main/scala/gitbucket/core/controller/RepositorySettingsController.scala
@@ -147,7 +147,7 @@
       // Update database
       renameRepository(repository.owner, repository.name, repository.owner, form.repositoryName)
     }
-    flash += "info" -> "Repository settings has been updated."
+    flash.update("info", "Repository settings has been updated.")
     redirect(s"/${repository.owner}/${form.repositoryName}/settings/options")
   })
 
@@ -167,7 +167,7 @@
       using(Git.open(getRepositoryDir(repository.owner, repository.name))) { git =>
         git.getRepository.updateRef(Constants.HEAD, true).link(Constants.R_HEADS + form.defaultBranch)
       }
-      flash += "info" -> "Repository default branch has been updated."
+      flash.update("info", "Repository default branch has been updated.")
       redirect(s"/${repository.owner}/${repository.name}/settings/branches")
     }
   })
@@ -231,7 +231,7 @@
    */
   post("/:owner/:repository/settings/hooks/new", webHookForm(false))(ownerOnly { (form, repository) =>
     addWebHook(repository.owner, repository.name, form.url, form.events, form.ctype, form.token)
-    flash += "info" -> s"Webhook ${form.url} created"
+    flash.update("info", s"Webhook ${form.url} created")
     redirect(s"/${repository.owner}/${repository.name}/settings/hooks")
   })
 
@@ -240,7 +240,7 @@
    */
   get("/:owner/:repository/settings/hooks/delete")(ownerOnly { repository =>
     deleteWebHook(repository.owner, repository.name, params("url"))
-    flash += "info" -> s"Webhook ${params("url")} deleted"
+    flash.update("info", s"Webhook ${params("url")} deleted")
     redirect(s"/${repository.owner}/${repository.name}/settings/hooks")
   })
 
@@ -350,7 +350,7 @@
    */
   post("/:owner/:repository/settings/hooks/edit", webHookForm(true))(ownerOnly { (form, repository) =>
     updateWebHook(repository.owner, repository.name, form.url, form.events, form.ctype, form.token)
-    flash += "info" -> s"webhook ${form.url} updated"
+    flash.update("info", s"webhook ${form.url} updated")
     redirect(s"/${repository.owner}/${repository.name}/settings/hooks")
   })
 
@@ -390,7 +390,7 @@
         git.gc().call()
       }
     }
-    flash += "info" -> "Garbage collection has been executed."
+    flash.update("info", "Garbage collection has been executed.")
     redirect(s"/${repository.owner}/${repository.name}/settings/danger")
   })
 
diff --git a/src/main/scala/gitbucket/core/controller/RepositoryViewerController.scala b/src/main/scala/gitbucket/core/controller/RepositoryViewerController.scala
index 7ae412e..8e238b2 100644
--- a/src/main/scala/gitbucket/core/controller/RepositoryViewerController.scala
+++ b/src/main/scala/gitbucket/core/controller/RepositoryViewerController.scala
@@ -792,10 +792,10 @@
       JGitUtil.createTag(git, form.tagName, form.message, form.commitId)
     } match {
       case Right(message) =>
-        flash += "info" -> message
+        flash.update("info", message)
         redirect(s"/${repository.owner}/${repository.name}/commit/${form.commitId}")
       case Left(message) =>
-        flash += "error" -> message
+        flash.update("error", message)
         redirect(s"/${repository.owner}/${repository.name}/commit/${form.commitId}")
     }
   })
@@ -810,12 +810,12 @@
       JGitUtil.createBranch(git, fromBranchName, newBranchName)
     } match {
       case Right(message) =>
-        flash += "info" -> message
+        flash.update("info", message)
         redirect(
           s"/${repository.owner}/${repository.name}/tree/${StringUtil.urlEncode(newBranchName).replace("%2F", "/")}"
         )
       case Left(message) =>
-        flash += "error" -> message
+        flash.update("error", message)
         redirect(s"/${repository.owner}/${repository.name}/tree/${fromBranchName}")
     }
   })
diff --git a/src/main/scala/gitbucket/core/controller/SystemSettingsController.scala b/src/main/scala/gitbucket/core/controller/SystemSettingsController.scala
index 2b7174d..a71c83f 100644
--- a/src/main/scala/gitbucket/core/controller/SystemSettingsController.scala
+++ b/src/main/scala/gitbucket/core/controller/SystemSettingsController.scala
@@ -305,7 +305,7 @@
       } SshServer.start(sshAddress, baseUrl)
     }
 
-    flash += "info" -> "System settings has been updated."
+    flash.update("info", "System settings has been updated.")
     redirect("/admin/system")
   })
 
@@ -333,7 +333,7 @@
 
   post("/admin/plugins/_reload")(adminOnly {
     PluginRegistry.reload(request.getServletContext(), loadSystemSettings(), request2Session(request).conn)
-    flash += "info" -> "All plugins were reloaded."
+    flash.update("info", "All plugins were reloaded.")
     redirect("/admin/plugins")
   })
 
@@ -343,7 +343,7 @@
     if (PluginRegistry().getPlugins().exists(_.pluginId == pluginId)) {
       PluginRegistry
         .uninstall(pluginId, request.getServletContext, loadSystemSettings(), request2Session(request).conn)
-      flash += "info" -> s"${pluginId} was uninstalled."
+      flash.update("info", s"${pluginId} was uninstalled.")
     }
 
     redirect("/admin/plugins")
@@ -391,7 +391,7 @@
     getAccountByUserName(userName, true).map {
       account =>
         if (account.isAdmin && (form.isRemoved || !form.isAdmin) && isLastAdministrator(account)) {
-          flash += "error" -> "Account can't be turned off because this is last one administrator."
+          flash.update("error", "Account can't be turned off because this is last one administrator.")
           redirect(s"/admin/users/${userName}/_edituser")
         } else {
           if (form.isRemoved) {
diff --git a/src/main/scala/gitbucket/core/controller/WikiController.scala b/src/main/scala/gitbucket/core/controller/WikiController.scala
index 319f19f..2c9764e 100644
--- a/src/main/scala/gitbucket/core/controller/WikiController.scala
+++ b/src/main/scala/gitbucket/core/controller/WikiController.scala
@@ -139,7 +139,7 @@
       if (revertWikiPage(repository.owner, repository.name, from, to, context.loginAccount.get, Some(pageName))) {
         redirect(s"/${repository.owner}/${repository.name}/wiki/${StringUtil.urlEncode(pageName)}")
       } else {
-        flash += "info" -> "This patch was not able to be reversed."
+        flash.update("info", "This patch was not able to be reversed.")
         redirect(
           s"/${repository.owner}/${repository.name}/wiki/${StringUtil.urlEncode(pageName)}/_compare/${from}...${to}"
         )
@@ -154,7 +154,7 @@
       if (revertWikiPage(repository.owner, repository.name, from, to, context.loginAccount.get, None)) {
         redirect(s"/${repository.owner}/${repository.name}/wiki")
       } else {
-        flash += "info" -> "This patch was not able to be reversed."
+        flash.update("info", "This patch was not able to be reversed.")
         redirect(s"/${repository.owner}/${repository.name}/wiki/_compare/${from}...${to}")
       }
     } else Unauthorized()