Error: The ValidateAddInXMLTask task failed unexpectedly...

Error Message

When compiling an ArcObjects add-in using Microsoft Visual Studio 2015, the following error may be returned:

"The ValidateAddInXMLTask task failed unexpectedly. System.IO.FileNotFoundException:
Could not load file or assembly 'Microsoft.VisualStudio.Shell.12.0, Version=,
Culture=neutral, PublicKeyToken=b03f5f7f11d50a3a' or one of its dependencies.
The system cannot find the file specified."



ArcGIS Desktop and Engine add-ins have a dependency on the Microsoft Visual Studio Shell 12.0 library.

This error occurs when using Visual Studio 2015 without this library.

If Visual Studio 2013 and 2015 are both installed on the machine, this problem does not occur. Visual Studio 2013 includes the Microsoft Visual Studio Shell 12.0 library.

Solution or Workaround


  1. To resolve this issue, download and install the Microsoft Visual Studio 2013 Shell (Isolated) redistributable Package.
  2. Compile the add-in again with Visual Studio 2015.