The ORA-39126 error in KUPW$WORKER.PREPARE_DATA_IMP [71] indicates an internal Data Pump failure during import, often caused by corrupted Data Pump catalogs, PDB/CDB mismatches, or issues within the temporary tablespace. Resolving the issue typically involves validating the Data Pump catalog, ensuring the temporary tablespace is valid, or using the EXCLUDE=STATISTICS parameter. For a detailed troubleshooting guide, refer to Oracle Communities

When the worker encounters a "fatal error" at this stage, it means the process cannot proceed because the metadata or data stream is inconsistent, corrupted, or incompatible with the target database. The worker does not merely throw a warning; it halts the entire import operation.

impdp ... table_exists_action=truncate

SELECT * FROM v$pgastat;

This error typically indicates that a worker process, which is responsible for executing a specific task during the import operation, encountered an unexpected fatal error while preparing data for import.

# Use DBMS_DATAPUMP to validate impdp user/pwd DIRECTORY=dp_dir DUMPFILE=exp.dmp SQLFILE=check.sql