XamlParseException after deploying WPF project

This is normally caused by not having all dependencies copied to the output. As you say the error message is not very helpful, but I would check that your application has all the necessary dependencies available to resolve the parsed types.

Normally it is enough to set Copy Local to true for referenced assemblies, but I've experienced some cases where references themselves reference assemblies, so it can be necessary to explicitly add those references as well.

Update:

Important addition by @BENN1TH.

If you want to see what an assembly is necessary:

Was getting the same type of issue once i had published and installed my project (was working fine in debug VS2013 Desktop, no errors etc) but used the advice in from http://geekswithblogs.net/lbugnion/archive/2007/03/14/108728.aspx and wham! installed project was working..

try{  InitializeComponent();}catch ( Exception ex ){  // Log error (including InnerExceptions!)  // Handle exception}

Cleaning and Rebuilding the solution might help!

I had this problem with a WPF solution in VS2010. The solution contained a simple dll and a test project (set to startup) for testing the dll. My dll was set to x86 and my test project was set to x64. When I changed the test project to x86 the problem was resolved.