Diagnosis
You want to activate one or more traces. However one or more traces arealready activated for one or all users.
Since the trace can only be activated for one or all users you cannotchange the trace switch.

System Response
After the message the system continues working.

Procedure
Wait until the trace has been deactivated by the user.
If necessary contact the user who activated the trace. You can find theuser name on the screen "Trace requests" (initial screen of thetransaction) under the heading "State of traces".