The type initializer for 'Telerik.JustMock.SecuredReflection' threw an exception

Updated on Jan 27, 2026

Description

When JustMock is referenced from the installation folder, it is possible to get the following exception during test run:

System.TypeInitializationException : The type initializer for 'Telerik.JustMock.SecuredReflection' threw an exception. ---- System.IO.FileNotFoundException : Could not load file or assembly 'System.Security.Permissions, Version=4.0.1.0, Culture=neutral, PublicKeyToken=cc7b13ffcd2ddd51'. The system cannot find the file specified.

Solution

Add reference to System.Security.Permissions' nuget package. Target versions greater than 4.0.1.0.