Ora-39126 Worker Unexpected Fatal Error In Kupw-worker.prepare-data-imp 71 -

If internal packages are corrupted, you may need to reload the Data Pump utility:

The Oracle error is a generic "catch-all" message indicating that a Data Pump worker process has encountered an unhandled exception. When specifically paired with the module KUPW$WORKER.PREPARE_DATA_IMP [71]

Refreshing the database's internal statistics often resolves these internal worker errors.