Oracle Error Message
ORA-15504: cannot start workload capture because instance string not present in RESTRICTED SESSION mode
Reason for the Error
The NO_RESTART_MODE option in DBMS_WORKLOAD_CAPTURE.START_CAPTURE was FALSE, therefore all the active instances were expected to be in the RESTRICTED SESSION mode.
Solution
Start all instances using STARTUP RESTRICT or execute ALTER SYSTEM ENABLE RESTRICTED SESSION on all active instances before issuing DBMS_WORKLOAD_CAPTURE.START_CAPTURE.