Could not load file or assembly 'System, Version=4.0.0.0, Culture=neutral, PublicKeyToken=b77a5c561934e089' or one of its dependencies
.net, c#, frameworks
Solution
I had this same problem - some users could pull from git and everything ran fine. Some would pull and get a very similar exception:
Could not load file or assembly '..., Version=..., Culture=neutral, PublicKeyToken=...' or one of its dependencies. The system cannot find the file specified.
In my particular case it was AjaxMin, so the actual error looked like this but the details don't matter:
Could not load file or assembly 'AjaxMin, Version=4.95.4924.12383, Culture=neutral, PublicKeyToken=21ef50ce11b5d80f' or one of its dependencies. The system cannot find the file specified.
It turned out to be a result of the following actions on a Solution:
NuGet Package Restore was turned on for the Solution.
A Project was added, and a Nuget package was installed into it (AjaxMin in this case).
The Project was moved to different folder in the Solution.
The Nuget package was updated to a newer version.
And slowly but surely this bug started showing up for some users.
The reason was the Solution-level packages/respositories.config kept the old Project reference, and now had a new, second entry for the moved Project. In other words it had this before the reorg:
<repository path="..\Old\packages.config" />
And this after the reorg:
<repository path="..\Old\packages.config" />
<repository path="..\New\packages.config" />
So the first line now refers to a Project that, while on disk, is no longer part of my Solution.
With Nuget Package Restore on, both packages.config files were being read, which each pointed to their own list of Nuget packages and package versions. Until a Nuget package was updated to a newer version however, there weren't any conflicts.
Once a Nuget package was updated, however, only active Projects had their repositories listings updated. NuGet Package Restore chose to download just one version of the library - the first one it encountered in repositories.config, which was the older one. The compiler and IDE proceeded as though it chose the newer one. The result was a run-time exception saying the DLL was missing.
The answer obviously is to delete any lines from this file that referenced Projects that aren't in your Solution.
Problem
I have this exception generated on some user machines (~1 of 20): Could not load file or assembly 'System, Version=4.0.0.0, Culture=neutral, PublicKeyToken=b77a5c561934e089' or one of its dependencies. The system cannot find the file specified. I found several references to this error over the web and this site but nothing helped. I have an add-in application which uses WCF to connect to the server. The add-in built with .NET Framework 3.5 with VS 2008. The error is reproducible on one of the test machines in only one user account. I install my application and can only reproduce this from one account on this machine everywhere else it is working fine. Furthermore it is only reproducible with only one version of host application which I created add-in for (I assume because it uses differnet .NET Frameworks). I have checked the fuse logs and I see the following: ``` Assembly manager loaded from: C:\Windows\Microsoft.NET\Framework64\v2.0.50727\mscorwks.dll Running under executable C:\Program Files\SolidWorks Corp\SolidWorks\sldworks.exe --- A detailed error log follows. === Pre-bind state information === LOG: User = Home\User LOG: DisplayName = System, Version=4.0.0.0, Culture=neutral, PublicKeyToken=b77a5c561934e089 (Fully-specified) LOG: Appbase = file:///C:/Program Files/SolidWorks Corp/SolidWorks/ LOG: Initial PrivatePath = NULL LOG: Dynamic Base = NULL LOG: Cache Base = NULL LOG: AppName = NULL Calling assembly : System.Configuration, Version=2.0.0.0, Culture=neutral, PublicKeyToken=b03f5f7f11d50a3a. ``` So by some reasons it is trying to use `v2.0.50727\mscorwks.dll` loader to load the `Version=4.0.0.0` of `System.dll`. On build machine I'm referring 2.0.0.0 version of `System.dll`.