A serious error occurred : Sitecore Experience Editor

Last week I have written a blog post about how to solve a mysterious Experience Editor error "An error occurred". This time I have again stumbled upon a similar error in experience editor (Sitecore 8.1 update 3).

A serious error occurred please contact the administrator.

As stated in my last blog post that there could be multiple reasons of such type of error. I’ve started the troubleshooting and noticed below two exceptions in log file:

Exception 1:

ERROR Error processing command url:/-/speak/request/v1/expeditor/ExperienceEditor.Social.SocialCenter.GetMessagesCount error:System.InvalidOperationException: Could not retrieve request class for url:/-/speak/request/v1/expeditor/ExperienceEditor.Social.SocialCenter.GetMessagesCount
   at Sitecore.ExperienceEditor.Speak.Server.RequestHandler.Process(HttpContext context)
   at Sitecore.ExperienceEditor.Speak.Server.RequestHandler.ProcessRequest(HttpContext context)

Exception 2:

ERROR Error processing command url:/-/speak/request/v1/expeditor/Optimization.ActiveItemTest error:System.InvalidOperationException: Could not retrieve request class for url:/-/speak/request/v1/expeditor/Optimization.ActiveItemTest
   at Sitecore.ExperienceEditor.Speak.Server.RequestHandler.Process(HttpContext context)
   at Sitecore.ExperienceEditor.Speak.Server.RequestHandler.ProcessRequest(HttpContext context)

Solving exception 1:
Exception 1 was related to Sitecore Social connect. We are using Sitecore in CMS only mode and have disabled Sitecore Social Connector config files. After troubleshooting, I’ve archived below item in core database so that it won’t appear in experience editor ribbon
/sitecore/content/Applications/WebEdit/Ribbons/WebEdit/Page Editor/Social
Solving exception 2:

Exception 2 was related to Sitecore Content Testing. We were not using Sitecore Content Testing and disabled all the App_Config\Include\ContentTesting\*.config files. After troubleshooting, I found that Content Testing related features are not completely disabled by disabling config files. I was able to disable content testing completely by disabling InjectOptimizationViewMode.js file. To disable js file, navigate to the \Website\sitecore\shell\client\Sitecore\ExperienceEditor\Pipelines\InitializePageEdit folder, and change the InjectOptimizationViewMode.js file extension to .disabled.

I hope this blog post is helpful to some of you and save few minutes of troubleshooting. If this solution doesn’t help you then make sure to check out other blogs/SO posts related to this error as there can be other reasons for this “A serious error occurred please contact the administrator” error.  Comments and suggestions are most welcome. Happy coding!