Ora-39126 Worker Unexpected Fatal Error In Kupw-worker.prepare-data-imp 71 ^hot^ (2026)

Sometimes reducing or increasing PARALLEL helps:

Understanding and Resolving ORA-39126: Worker Unexpected Fatal Error in KUPW$WORKER.PREPARE_DATA_IMP [71]

Oracle Data Pump ( impdp ) is a powerful utility, but it can sometimes throw obscure errors that halt migration or backup restoration. One such frustrating error is the .

The dump file was created in a higher version of Oracle and is being imported into a lower version (e.g., 19c to 12c) without proper compatibility settings. but in practice

SELECT comp_id, comp_name, version, status FROM dba_registry; SELECT owner, object_name, object_type, status FROM dba_objects WHERE status = 'INVALID' AND object_name IN ('DBMS_METADATA', 'KUPW$WORKER'); Use code with caution.

The fans in the server rack roared. The logs began to scroll again. 90%... 95%... 100%.

The most frequent cause of error [71] is a failure in processing table statistics. You can bypass this by excluding statistics during the import and gathering them manually later. Add this parameter to your impdp command: EXCLUDE=STATISTICS Use code with caution. as they can trigger internal errors.

The ORA-39126 error is not a single issue but a symptom of many potential problems. The official Oracle documentation defines it as an internal error, but in practice, the root causes often fall into the following categories:

If you are still experiencing this error, ensure your database is updated to the latest patch set to resolve known DBMS_METADATA bugs.

: Run the following on the source database to ensure no invalid objects are exported, as they can trigger internal errors. 90%... 95%... 100%.

ORA-39126: Worker unexpected fatal error in KUPW-Worker.Prepare-Data-Imp 71

Since the error is internal, invalid SYS packages are a prime suspect.

The error occurs during an impdp operation, typically after the table has been created or truncated but before rows are inserted. It can happen with: