Wednesday, 4 December 2013

Error Deploying Visual Studio Workflows: Assembly signing failed

Hello Guys.

I had this C# Visual Studio 2013 code which was already in use, I had made modifications to it and it really needed to be deployed. But Alas, I click on "Deploy" and get the error message below

Error 1 Assembly signing failed; output may not be signed -- Error signing assembly -- The process cannot access the file because it is being used by another process.  {SolutionName}

I stopped for a moment to think what was done wrongly. I tried Cleaning, Rebuilding, Closing and Reopening the solution. But Alas, to no avail.

Then I checked all the opened projects and found out that the same signed on user had opened the same project solution. So all I had to do was close the close other opened project solution with the same name, deployed, and Viola, ERROR DISAPPEARED

So whenever you come across this such errors, check your opened projects.


  1. Thanks Okwukwe,
    I just ran into this problem,
    How do I see if it is indeed open somewhere?

    1. Hello Deric,

      Sorry this may be late, but it could help someone else.
      To see if its opened, just look out for the opened Visual studio projects, when you find the duplicate of the one giving the error, close it and the problem would be resolved

  2. Thanks it works for me

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  4. I had the same issue and my Anti Virus was blocking the process. Added my code to the exclusions list and all was fine.