Examle B1 - Exception Handler

Example B1 is running for me without issue except I’m getting this text at the start

-------- WWWW ------- G4Exception-START -------- WWWW -------

*** ExceptionHandler is not defined ***
*** G4Exception : UI0002
issued by : G4UIExecutive::G4UIExecutive()
Specified session type is not build in your system,
or no session type is specified.
A fallback session type is used.
*** This is just a warning message. ***
-------- WWWW ------- G4Exception-END -------- WWWW -------

I’ve found other posts with the same issue, but the fix was to make sure all the environment variables were set correctly, which I have done. I can’t find any explanation of what the exception handler is or why this is happening. For reference, I’m on Windows 10 using Visual Studio. Thanks in advance for any help.