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

Question

Maybe this helps:

1. Delete the contents from the following folders:
   1. C:\Users\%userprofile%\AppData\Local\Microsoft\VisualStudio
   2. C:\Users\%userprofile%\AppData\Local\Microsoft\VSCommon
2. Sometimes, you need to go to:
   1. [x64] C:\Program Files (x86)\Microsoft Visual Studio 14.0\Common7\IDE
   2. [x86] C:\Program Files\Microsoft Visual Studio 14.0\Common7\IDE

and run devenv /resetuserdata.

Expect, that all of your user settings such as Visual Studio layout, linked Microsoft account or start page might disappear.

Delete %LocalAppData%\Microsoft\VisualStudio\14.0\ComponentModelCache and restart Visual Studio.

Alternatively, use the Clear MEF Component Cache extension.

For me,

1. I ended the process in Windows Task Manager: VsHub.exe.
2. Restarted Visual Studio.

After that, everything works like a charm again!

I solved it doing

run devenv /resetuserdata

in this path:

[x64] C:\Program Files (x86)\Microsoft Visual Studio 14.0\Common7\IDE

I assume that in x86 it works in this path:

[x86] C:\Program Files\Microsoft Visual Studio 14.0\Common7\IDE

It's recommended to try any or all of the following:

• Restart Visual Studio

• Try Running As Administrator (right-click Visual Studio and choose "Run As Administrator")

• Check for any updates for Visual Studio (download and install them if any are available)

• Try opening a different solution / project

If problems persist, you might try the following options:

• Restart your local machine

• Attempt to reset Visual Studio to System Defaults (this can be done from the options within Visual Studio)

• Attempt to repair your Visual Studio installation

In the hopes it might narrow things down/help someone, I did an investigatory approach. For me, I initially moved the folder at C:\Users\{user}\AppData\Local\Microsoft\VisualStudio to My Documents and allowed Visual Studio to re-create it by re-launching it. This removed the errors. So I moved everything back, one-by-one, and restarted Visual Studio each time until I discovered the culprits. These folders were fine to move back in:

• 1033 (overwrote the auto-generated copy with old)
• Designer (was in my old copy, not initially re-created when I re-launched VS, copied it back in)
• Extensions (overwrote the auto-generated copy with old)
• ImageLibrary (overwrote the auto-generated copy with old)
• Notifications (overwrote the auto-generated copy with old)
• STemplate (was in my old copy, not initially re-created when I re-launched VS, copied it back in)
• VTC (was in my old copy, not initially re-created when I re-launched VS, copied it back in)

These files were fine to move back in/overwrite the auto-generated ones:

• ApplicationPrivateSettings (was in my old copy, not initially re-created when I re-launched VS)
• ApplicationPrivateSettings.lock (overwrote the auto-generated copy with old)
• vspdmc.lock (overwrote the auto-generated copy with old)

These files were fine to move back in. Each was in my old copy, and not initially re-created when I re-launched VS:

• .NETFramework,Version=v4.0,Set=Framework,Hash=C958D412.dat
• .NETFramework,Version=v4.0,Set=RecentAssemblies,Hash=0.dat
• .NETFramework,Version=v4.5,Set=Extensions,Hash=75EAE334.dat
• .NETFramework,Version=v4.5,Set=Extensions,Hash=497525A2.dat
• .NETFramework,Version=v4.5,Set=Framework,Hash=5AE9A175.dat
• .NETFramework,Version=v4.5.2,Set=Extensions,Hash=24CEEB0D.dat
• .NETFramework,Version=v4.5.2,Set=Extensions,Hash=72AE305.dat
• .NETFramework,Version=v4.5.2,Set=Extensions,Hash=ADF899D7.dat
• .NETFramework,Version=v4.5.2,Set=Framework,Hash=D8E943A2.dat

These caused problems - delete these files and re-launch VS to allow it to re-create them:

• ComponentModelCache - When I overwrote this folder's contents with my old ones (4 files: MS.VS.Default.cache, .catalogs, .err, .external), this gave me all of the errors I had gotten before about not being able to load packages when loading my project, and the "object reference not set to an instance of an object" error when trying to close VS.
• devenv.exe.config - same as ComponentModelCache
• .NETFramework,Version=v4.0,Set=Extensions,Hash=6D09DECC.dat - causes error output from the JavaScript Language Service, complaining of missing js files
• .NETFramework,Version=v4.0,Set=Extensions,Hash=9951BC03.dat - causes error output from the JavaScript Language Service, complaining of missing js files
• .NETFramework,Version=v4.5.2,Set=RecentAssemblies,Hash=0.dat - causes error output from the JavaScript Language Service, complaining of missing js files

These are the errors from those last .NETFramework files (which I do not get if I do not add them back in):

01:10:11.7550: Referenced file 'C:\Program Files (x86)\Microsoft Visual Studio 14.0\JavaScript\References\libhelp.js' not found.
01:10:11.7550: Referenced file 'C:\Program Files (x86)\Microsoft Visual Studio 14.0\JavaScript\References\sitetypesWeb.js' not found.
01:10:11.7550: Referenced file 'C:\Program Files (x86)\Microsoft Visual Studio 14.0\JavaScript\References\domWeb.js' not found.
01:10:11.7550: Referenced file 'C:\Program Files (x86)\Microsoft Visual Studio 14.0\JavaScript\References\underscorefilter.js' not found.
01:10:11.7550: Referenced file 'C:\Program Files (x86)\Microsoft Visual Studio 14.0\JavaScript\References\showPlainComments.js' not found.

I might just need to re-install/repair the JavaScript Language Service plug-in, so it might be un-related. But definitely devenv.exe.config and ComponentModelCache need to go to correct the "object reference not set to an instance of an object" error.

For me, ASP.NET 5 is not yet required, I removed update, and then reinstalled ASP.NET 4.5. It's a bit tricky:

1. Removed from control panel "Microsoft ASP.NET 5 RC1 Update1". After that, you will no longer open ASP.NET MVC projects
2. Then I changed the installation of "Microsoft Visual Studio Professional 2015", clicked "Modify", and selected "Microsoft Web Developer Tools"

No longer follow the notification of update in Visual Studio 2015!!!