I get this error message when I try to deploy my project:

Error occurred in deployment step 'Add solution': The located assembly's manifest definition does not match the assembly reference. (Exception from HRESULT:0x80131040)

Earlier I had added some code to a visual webpart.

What I have done: - restarted VS 2010 - restarted pc - clean - retract - rebuild - after done all this I have taken a deploy.

  • Do you have any references in your project, to some third-party assemblies? Commented May 3, 2011 at 14:06

2 Answers 2


Looks like you have added custom developed DLL to the project referances. And later made updates to that DLL and updated in the GAC but not in the project. So, In the Project Referances remove the existing referance to the DLL and add it again.

Hope this helps

Thanks Chinna


Compare the versions of any DLLs in your project References to those in the solution package Additional Assemblies listed in the Advanced tab. Make sure they are both pointing to the same DLL.

Also, if the project you are deploying is referencing another project, check that project's references as well.

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