Visual Studio error “Object reference not set to an instance of an object” after install of ASP.NET and Web Tools 2015

Question

After installing the ASP.NET and Web Tools 2015 (RC1 update 1) I get the following error within ASP.NET MVC 4 projects when opening *.cshtml files:

Answer 1

Problem: My VS 2015 was throwing up error after I installed SSDT. Whenever I clicked on Tools >> Extensions and Update it was throwing "Object reference not set to an instance of an object" error. When I tried to open a solution it threw some provider not set correctly.

Solution: After many hours of research trying out all the solutions previously mentioned by others didn't solve my problem. Every time the error popup was pointing to check the ActivityLog.xml. But I was ignoring it. After hours of frustration I decided to read the error carefully and looked into ActivitLog.xml and found that it was looking for "Could not load file or assembly 'System.Collections.Immutable, Version=1.1.37.0". So I just started searching for this assembly and stumbled upon this link https://sergeytihon.com/2015/12/01/how-to-restore-viual-studio-2015-after-update-1-dependency-dance/ and followed the steps there, which fixed my issue.

Went into %LOCALAPPDATA%/Local\Microsoft\VisualStudio\14.0\devenv.exe.config and searched for "System.Collections.Immutable" and change newVersion from 1.1.36.0 to 1.1.37.0

Final config should look like this