After installing my X3 instance, when I try to access the XTrem Explorer URL (http://localhost:8124/xtrem/explorer) I get the following error:
Cannot read properties of null (reading 'x3ServiceClientId')
You could see this error in two situations:
1. You do not have a valid X3 session. i.e. you must login to X3 before the XTrem Explorer will allow access
2. "X3 Service" has not been selected in Administration, Administration, Endpoints, X3 Solution