Through analysis of numerous incident reports and Oracle Support documentation, several recurring causes have been identified:
The structure of the error message is critical for diagnosis:
[IMPDP Client] │ ▼ [Master Process (DM00)] ────► Coordinates the job │ ▼ [Worker Process (DW00)] ────► Executes PREPARE_DATA_IMP [71] ──► [CRASH]
How it helps : This bypasses the problematic metadata preparation phase entirely, only loading row data. Command :
Also, reduce the number of parallel workers: Through analysis of numerous incident reports and Oracle
Prevention is far more efficient than cure. To minimize the risk of ORA-39126:
The error occurs when the Data Pump worker process encounters a condition it doesn't know how to handle. In the context of PREPARE_DATA_IMP [71] , the most common culprits are:
The error is a generic "catch-all" internal error during an Oracle Data Pump import ( impdp ). It typically signifies an unhandled exception triggered by corrupted metadata, invalid system objects, or specific version incompatibilities . Common Root Causes
He scrambled to check the log file, his fingers shaking slightly over the keyboard. In the context of PREPARE_DATA_IMP [71] , the
To avoid this error in the future:
The Oracle Data Pump worker process encountered an unexpected fatal error while preparing data for import. The specific error code is "ora-39126" and the error message indicates that the issue occurred in the KUPW_WORKER.PREPARE_DATA_IMP module.
To resolve the ORA-39126 error, follow these troubleshooting steps:
Check if the failure happens on a specific object like an XMLType or a materialized view. To avoid this error in the future: The
Try adding ACCESS_METHOD=EXTERNAL_TABLE or ACCESS_METHOD=DIRECT_PATH.
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.
Data Pump remains one of the most powerful tools in the Oracle DBA’s arsenal. With patience and the right diagnostic approach, even a "fatal error" becomes a solvable puzzle.