Error in Visual Studio 2015 When Add New WebForm

Question

When I add new WebForm to my project, I get the following error:

Could not load file or assembly \'Microsoft.VisualStudio.JSLS,Vers

Answer 1

A temporary solution:

Shut down Visual Studio and reinstall the following package from the DVD or ISO:

x:\packages\JavaScript_LanguageService\JavaScript_LanguageService.msi

A better solution, endorsed by Microsoft, has been posted.

Answer 2

This is a known bug with Visual Studio 2015. The officially-endorsed solution from Microsoft has been posted on MSDN:

If the “Tools for Universal Windows Apps Development” are still installed:

1. Go to Programs and Features, select Visual Studio 2105, click Change.
2. In Visual Studio setup, click Modify.
3. Deselect the feature “Tools for Universal Windows App Development”
4. Select “Tools for Universal Windows App Development” again, and click Update.

If you have already uninstalled the “Tools for Universal Windows Apps Development”:

1. Reinstall “Tools for Universal Windows App Development”

2. Or take the following steps to reinstall the JavaScript project system and language service:

   a. Download the installer for your edition of Visual Studio, e.g.,
   vs_community.exe.

   b. Open a CMD window, and run the following command: vs_community.exe /modify /installselectableitems JavaScript_Hidden
   /passive

Answer 3

Remove the update received for visual studio TypeScript on 11/08/2015. it seems to be buggy. After removing TypeScript update, my VS is working fine ;-)

and if you try to reinstall x:\packages\JavaScript_LanguageService\JavaScript_LanguageService.msi from the installation package, soon or later you will face one more problem that "Something went wrong.. may be because of a extension.." Easiest way is to remove TypeScript update for now. TypeScript future update may fix the problem.

OR

1. Run command prompt as administrator.
2. CD C:\Program Files (x86)\Microsoft Visual Studio 14.0\Common7\IDE
3. devenv /updateconfiguration
4. devenv /clearcache