we see this error in the daily full=Y backup :

Processing object type DATABASE_EXPORT/SCHEMA/PROCACT_SCHEMA
ORA-39127: unexpected error from call to TAG: SCHEDULER Calling: SYS.DBMS_SCHED_CLASS_EXPORT.GRANT_EXP obj: SYS.IDX_RB$CLASS_54724 - SCHEDULER CLASS
ORA-01031: insufficient privileges
ORA-06512: at "SYS.DBMS_SCHED_MAIN_EXPORT", line 2601
ORA-06512: at "SYS.DBMS_SCHED_CLASS_EXPORT", line 41
ORA-06512: at line 1
ORA-06512: at "SYS.DBMS_SCHED_MAIN_EXPORT", line 2601
ORA-06512: at "SYS.DBMS_SCHED_CLASS_EXPORT", line 41
ORA-06512: at line 1
ORA-06512: at "SYS.DBMS_METADATA", line 11144
ORA-06512: at "SYS.DBMS_SYS_ERROR", line 95
Processing object type DATABASE_EXPORT/EARLY_POST_INSTANCE_IMPCALLOUT/MARKER


But, when we checked ( as sysdba) - this object dosn't exist in the container that it runs:
SYS.IDX_RB$CLASS_54724

no changes were made to the database/ shell script that runs the export datapump backup.

we had seen the same issue on 10th june 2024, but without any changes the next days export backups ran good.
yesterday - again the same error is seen.
not sure what could be causing it - here is the export command that we use for daily backup:
( the $vars are location/filenames generated in script)

expdp $pcsbackup job_name=${jobname}\
directory=DIR_DBEXP\
dumpfile=${dmpfile_name}\
logfile=${logfile_name}\
full=y\
cluster=no \
parallel=4\
exclude=STATISTICS\
exclude=SCHEMA:\" IN \(SELECT USERNAME FROM DBATOOL.EXPDP_EXCLUDE_DWP_BACKUP_TABLES\)\"\
ENCRYPTION=DATA_ONLY \
ENCRYPTION_PASSWORD=<OurProdEncPassowrd> \
ENCRYPTION_MODE=DUAL \
COMPRESSION=DATA_ONLY