I have Visual Studio 2012, 2013 and 2015 all installed on my machine. After installing Visual Studio 2013 Update 5, I started getting the "package did not load correctly" error in VS 2013.

All I did to get it working was to follow this step:

1. Close all instances of Visual Studio
2. Delete everything in this folder C:\Users\%username%\AppData\Local\Microsoft\VisualStudio\12.0\ComponentModelCache
3. Restart Visual Studio

Though I have not tried this for Visual Studio 2015, I believe this should solve the problem too. To do this for Visual Studio 2015, 12.0 should be changed to 14.0.

UPDATE

Instead of deleting everything in the folder (as suggested by step 2 above), it is much more safer to rename the folder and allow Visual Studio create a new one. Sometimes, you might have to copy somethings over from the old folder.

I've had the same problem with Visual Studio 2015 Community RTC and was able to fix this by deleting everything in:

1. C:\Users\<your users name>\AppData\Local\Microsoft\VisualStudio\14.0 and
2. C:\Users\<your users name>\AppData\Roaming\Microsoft\VisualStudio\14.0

So I would recommend trying this as you may be able to avoid uninstalling/reinstalling Visual Studio.

I also had a problem in Visual Studio 2015 RC.

There was a problem using menu File → New → Project... throwing an exception.

I followed the answer from Shittu Olugbenga, 2015-08-10, by deleting the content of folder: "C:\Users\\AppData\Local\Microsoft\VisualStudio\14.0\ComponentModelCache".

I restarted Visual Studio and it worked. :)

Due to extensions in Visual Studio 2015, I had to rename: C:\Users\\AppData\Local\Microsoft\VisualStudio\14.0

Once renamed, I opened Visual Studio 2015 and received more of these errors but the 14.0 folder was recreated.

I closed Visual Studio 2015 and copied the folders Extensions and STemplate from the original/renamed folder to the new one.

I reopened Visual Studio 2015 and all is working again.

Update 2015-09-24T0017:

It stopped working again. I tried all options in this post. I found another post and this seems to have worked:

Run:

devenv /clearcache
devenv /updateconfiguration

In my case for NugetPackage, the problem was possibly due to installing Visual Studio 2013 after installing Visual Studio 2015 (co-existing).

The way I resolved it was to re-install NuGet Package Manager for Visual Studio 2015 (in Tools > Extensions and Updates...)

One more workaround for Visual Studio 2015 Update 1

1. Open c:\Users\{User_Name}\AppData\Local\Microsoft\VisualStudio\14.0\devenv.exe.config
2. Change binding redirection for System.Collections.Immutable, newVersion should be 1.1.37.0 (not 1.1.36.0).

The redirection should look like this:

    <dependentAssembly>
<assemblyIdentity name="System.Collections.Immutable" publicKeyToken="b03f5f7f11d50a3a" culture="neutral"/>
<bindingRedirect oldVersion="1.0.27.0-1.1.65535.65535" newVersion="1.1.37.0"/>
</dependentAssembly>

Error from ActivityLog.xml:

SetSite failed for package [CSharpPackage][Could not load file or assembly 'System.Collections.Immutable, Version=1.1.36.0, Culture=neutral, PublicKeyToken=b03f5f7f11d50a3a' or one of its dependencies. The located assembly's manifest definition does not match the assembly reference. (Exception from HRESULT: 0x80131040)]:{ at Microsoft.VisualStudio.LanguageServices.Implementation.LanguageService.AbstractPackage`2.Initialize() at Microsoft.VisualStudio.LanguageServices.CSharp.LanguageService.CSharpPackage.Initialize() at Microsoft.VisualStudio.Shell.Package.Microsoft.VisualStudio.Shell.Interop.IVsPackage.SetSite(IServiceProvider sp)}

You can read more about how to troubleshoot such issues in my blog post How to restore Visual Studio 2015 after the Update 1.

My problem happened after installing Visual Studio 2015 Update 1.

I tried all suggested solutions without luck. The solution which worked for me was a one from Eric Knox (Microsoft team).

This is it:

1. Download the correct VSUpdate 1 configuration to a folder on your machine from this link: https://download.microsoft.com/download/2/7/6/276D15B2-6851-42AA-8D1F-639CD3FC84BE/devenv-exe-config-update1.xml

2. Open an administrator command prompt and run these steps (assuming you installed to the default location):

   cd "%ProgramFiles(x86)%\Microsoft Visual Studio 14.0\Common7\IDE"
   ren devenv.exe.config devenv.exe.config.backup
   copy <local path to file downloaded in step #1> .\devenv.exe.config
   devenv /UpdateConfiguration
   

You can check his full article here

The only thing that worked for me was repairing SQL Server Data Tools (go to Uninstall Programs and select Change/Repair):

When starting Microsoft Visual Studio Enterprise 15 Preview (version 15.0.25123), I had the same error:

<entry>
<record>27</record>
<time>2016/05/02 12:26:57.451</time>
<type>Error</type>
<source>VisualStudio</source>
<description>SetSite failed for package [Image Service Package]Source:
..
<guid>{1491E936-6FFE-474E-8371-30E5920D8FDD}</guid>
<hr>80131522</hr>
<errorinfo></errorinfo>
</entry>

I try to change the registry key, but it did not work.

It really never worked. Uninstall the previous version, but try it and it worked!

Uninstall Microsoft Visual Studio Ultimate 2015 Preview, (Version 14.0.23310)

It worked (for me :) )

I ran all of the tips in previous answers as well. I do not know if that's necessary or not.

Similar to @Tom Clelford's solution, but in addition to deleting everything in:

C:\Users{username}\AppData\Local\Microsoft\VisualStudio\14.0

I had to also delete everything in

C:\Users{username}\AppData\Local\Microsoft\VisualStudio\vshub

I didn't have to touch anything in the Roaming folder, but that might vary from user to user.

I had the same problem after upgrading to new ReSharper 2016.2. I fixed the problem by suspending the ReSharper in visual studio (menu Tools → Options → ReSharper → Suspend).