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Error loading type library/DLL (Microsoft.Office.Interop.Excel.Application)

I was struggling with this error for a few days . It came out after I’ve upgraded my project to Visual Studio 2012.

Unable to cast COM object of type ‘System.__ComObject’ to interface type ‘Microsoft.Office.Interop.Excel.Application’. This operation failed because the QueryInterface call on the COM component for the interface with IID ‘{000208D5-0000-0000-C000-000000000046}’ failed due to the following error: Error loading type library/DLL. (Exception from HRESULT: 0x80029C4A (TYPE_E_CANTLOADLIBRARY)).

It shows up while it’s the time for Excel operations:



It occurs because I’ve installed Office 2013 instead of Office 2010 which I was using with old version of my project. After I upgraded my Office, the project was no longer able to link Excel reference.

Even though I referenced new Excel library which is 15.0, it didn’t work.


  • Delete the Excel reference (Microsoft.Office.Interop.Excel). Version 15.0, in my case.
  • Install Microsoft Excel (whichever version you had been using. Version 2010 for me)
  • Add the Excel reference (older one. Version 14.0, in my case)

Long story short: Never take more than one risk at the same time!

Ned Sahin

Blogger for 20 years. Former Microsoft Engineer. Author of six books. I love creating helpful content and sharing with the world. Reach me out for any questions or feedback.

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