You have configured DBMS user management.
When you synchronize database management system (DBMS) user management with SAP NetWeaver Application Server (SAP NetWeaver AS) user management, you must periodically check that the users SAP NetWeaver AS expects are still available.
SAP NetWeaver AS provides the RSUSR_DBMS_USERS_CHECK report to check for all users that have a mapping to a DBMS user if the DBMS user exists. Use this report to either remove the mapping for missing DBMS users or create DBMS users.