Visual Studio 2010 Could not load file or assembly

Visual Studio build error: :
Error 15 Could not load file or assembly 'file:///C:\Documents and Settings\kumard\My Documents\Visual Studio 2010\Projects\LANSW.LMS\site\References\SwitchIT.DataAccess.dll' or one of its dependencies. Operation is not supported. (Exception from HRESULT: 0x80131515)


  • Right click on each *.dll file in Windows Explorer.
  • Uncheck “Read Only”.
  • Click “Unblock”.

If dll are stored in a network drive, move them locally and re-add your references.

Diganta Kumar is an experienced Technical Program Manager with a passion for technology. He has architected and developed software for over a decade for a broad range of industries. Diganta is a founder of two online IT businesses. He likes to help, mentor, and manage software development teams to improve and produce great software. He currently works as a Principal Program Manager for Microsoft. Before joining Microsoft, he was with AWS for five years, where he managed large cross-functional programs on a global scale.

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Posted in C#, Visual Studio
3 comments on “Visual Studio 2010 Could not load file or assembly
  1. Jens-Peter Giersch says:

    Are you sure that this resolves this issue?

    If I paste a path with “file:///” into the Windows Explorer, I get an error message stating the same: File not found.
    If I remove one of the slashes, everything works fine.
    But how do I tell VS2010 to use the correct path?

  2. I hate to admit it but you were right: Using a local location for the project files solved the problem.

    But I am a bit irritated: Isn’t it possible to put project files to a network drive? Not to helpful if I need to work on different machines…

  3. Andreas says:

    Thanks a lot , You’ve saved me lot’s of time , such an unpredictable solution was…

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