UT Editor Extension could not be activated - System.IO.FileNotFoundException: Newtonsoft.Json

Problem:

When starting the application or activating the UT Desktop Extension following error occurs.

UT Editor Extension could not be activated.
Error occurs on UT Editor Extension startup.
The type initializer for "AedSicad.UT.FoundationUI.ApplicationSupport" threw an exception
System.IO.FileNotFoundException: Newtonsoft.Json, Version=10.0.0.0, Culture=neutral, PublicKeyToken=30ad4fe6b2a6aeed'file or compilation, or one of its dependencies.

Cause:

The assembly Newtonsoft.Json is a 3rd party component, used within UT for ArcGIS and placed into the GAC during the installation. For unknown reasons it could happen, that the assembly for example after a Windows update isn't in the GAC anymore. Then this error occurs.

Solution:

After repairing the installation for UT for ArcGIS the assembly is in the GAC again and the error doesn't occur.