Error: Parser Error Message: Could not load type” in Global.asax

I resolved this error to change project OutputPath property to "bin" instead of "bin\Debug" or "bin\Release"

Go to the Project right click and select Property > Compile and change "Build output path" to "bin\"

or Unload project and open for Edit and Modify Outputpath property to "bin\" instead of "bin\Debug" or "bin\Release".
and also you can check IIS pool should be in correct .NET version (2.0 or 4.0)