The Enforce console displays a Code 3900 Internal communications error.
Detail: Internal communications error. Please see MonitorController.log for errors. Search for the sting TC – Unexpected exception.
This was caused by deleting two detection servers from the Enforce console but not uninstalling the Detection server software from their host server.
When the deleted Detection servers try to contact the Enforce server, this error will be created.
To resolve this error, uninstall the Detection server software for those Detection servers that have been deleted from the Enforce server.
See related KB 170745 if the error occurs on an Endpoint server instead of the Enforce server.