Message is not getting created in EXM

I have been working on Sitecore EXM (Email Experience Manager) for one POC and faced few issues with the EXM module. Recently I stuck in a situation where clicking the Create button does not create a new message in EXM. I am working with Sitecore 8 Update 5 and EXM 3.1 rev. 150811 (Update-1).

Clicking on create button doesn’t perform any action and the dialog window just hangs. A quick Google search has redirected me to this knowledge base article but unfortunately the given solution didn’t work in my case. On troubleshooting MessageCreationDialogBase.js (location : /sitecore/shell/client/Applications/ECM/EmailCampaign.Client/Dialog/MessageCreationDialogBase.js) I have found that .aspx extension is getting appended to createType.

I’ve modified javascript code and added below lines above switch statement code block:

    if(createType.includes('.aspx'))
    {
     createType = createType.slice(0,-5);
    }

Updated code:

   if(createType.includes('.aspx'))
    {
     createType = createType.slice(0,-5);
    }
          switch (createType) {
            case "ExistingTemplate":
              this.createExistingTemplate(contextApp, eventInfo);
              break;
            case "ExistingPage":
              this.createExistingPage(contextApp, eventInfo);
              break;
            case "ImportHtml":
              this.createImportHtml(contextApp);
              break;
            default:
          }

Clear browser cache and make sure that updated javascript file is getting loaded. Comments and suggestions are most welcome. Happy coding!