c# - The located assembly's manifest definition does not match the assembly reference

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I am trying to run some unit tests in
a C# Windows Forms application (Visual Studio 2005), and I get the following
error:

System.IO.FileLoadException: Could not load file or assembly 'Utility,
Version=1.2.0.200, Culture=neutral, PublicKeyToken=764d581291d764f7' or one of its
dependencies. The located assembly's manifest definition does not match the assembly
reference. (Exception from HRESULT: 0x80131040)**

at x.Foo.FooGO()

at
x.Foo.Foo2(String groupName_) in Foo.cs:line 123

at x.Foo.UnitTests.FooTests.TestFoo() in FooTests.cs:line
98**

System.IO.FileLoadException: Could not
load file or assembly 'Utility, Version=1.2.0.203, Culture=neutral,
PublicKeyToken=764d581291d764f7' or one of its dependencies. The located assembly's
manifest definition does not match the assembly reference. (Exception from HRESULT:
0x80131040)

I
look in my references, and I only have a reference to Utility version
1.2.0.203 (the other one is
old).

Any suggestions on how I figure out what
is trying to reference this old version of this DLL
file?

Besides, I don't think I even have this
old assembly on my hard drive.
Is there any tool to search for this old
versioned assembly?

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class="normal">Answer

The .NET
Assembly
loader:

• is
  unable to find 1.2.0.203


• but did find a
  1.2.0.200

This assembly
does not match what was requested and therefore you get this error.

In simple words, it can't find the assembly
that was referenced. Make sure it can find the right assembly by putting it in the GAC
or in the application path. Also see href="http://blogs.msdn.com/junfeng/archive/2004/03/25/95826.aspx" rel="nofollow
noreferrer">http://blogs.msdn.com/junfeng/archive/2004/03/25/95826.aspx.