Ora-39126 Worker Unexpected Fatal Error In Kupw-worker.prepare-data-imp 71 〈1080p〉

The error "ORA-39126: Worker unexpected fatal error in KUPW-WORKER.PREPARE-DATA-IMP 71" occurs during an Oracle Data Pump import operation (using impdp). It indicates that a worker process encountered a critical, unexpected failure while preparing to load data into a table or partition.

Immediate Diagnostic Steps

Quick Diagnostic One-Liner

impdp directory=DATA_PUMP_DIR dumpfile=your.dmp \
  transform=segment_attributes:n:lob_storage:n \
  exclude=statistics \
  parallel=1 \
  logfile=test.log

If the error persists, the dump file is likely irrecoverably corrupted, and you will need to recreate it from the source.

ORA-39126: Worker unexpected fatal error in KUPW$WORKER.PREPARE_DATA_IMP [71]

is a generic "unhandled exception" within the Data Pump worker process, typically occurring during the initial setup of an import job. While the code

identifies the specific internal routine failing, this error often stems from environment mismatches or corrupted Data Pump metadata. Potential Causes Permissions & Sessions : Running Data Pump as

can trigger unexpected behavior or performance issues; it is recommended to use a user with the DATAPUMP_IMP_FULL_DATABASE role instead. Metadata Corruption : The Data Pump packages or required views (like SYS.DBMS_METADATA ) might be invalid or missing. Version Mismatch

: Using a newer export version to import into an older database version without setting the parameter correctly. Resource Issues

: An empty or improperly configured default temporary tablespace can cause the worker process to fail during initial work item dispatch. Recommended Solutions The error "ORA-39126: Worker unexpected fatal error in

Diagnostic Methodology

Resolving ORA-39126 requires moving beyond a simple retry. The DBA must adopt a forensic approach:

  1. Examine the Complete Log: The error message typically includes a secondary exception. Using impdp ... LOGFILE=detailed.log may reveal a ORA-31623, ORA-39125, or ORA-01403 immediately preceding the fatal error. This secondary error is the key to the root cause.
  2. Identify the Culprit Table: The Data Pump log often names the table being imported when the error occurred. Isolating this table is critical.
  3. Test with SQLFILE Parameter: Run the import with impdp ... SQLFILE=ddl.sql. This generates the DDL without executing it. If the DDL fails to generate or contains anomalies, the metadata is corrupted.
  4. Check Versions: Compare the source and target database versions and patch levels. Mismatched versions (especially across major releases like 12.1 to 12.2) are common triggers.

Conclusion

The ORA-39126 error, while appearing cryptic and fatal, is not a random failure. It is the worker process signaling a fundamental incompatibility or corruption that prevents it from safely preparing the data import. By understanding its context—within the PREPARE-DATA-IMP subroutine of the KUPW worker—a DBA can systematically diagnose whether the issue lies in dump file corruption, metadata inconsistency, version mismatch, or a known software bug. Resolution ranges from re-exporting data and applying patches to isolating problematic objects. Ultimately, disciplined preventive practices and a calm, methodical diagnostic approach transform this intimidating error from a showstopper into a solvable challenge. In the world of database administration, errors like ORA-39126 remind us that even robust utilities demand respect, understanding, and rigorous preparation.

ORA-39126: Worker unexpected fatal error in KUPW$WORKER.PREPARE_DATA_IMP [71]

a Data Pump internal error that typically occurs when the worker process encounters an unhandled exception during the preparation phase of an import . The specific code is often associated with underlying ORA-01403: no data found errors in the internal Data Pump packages. Oracle Communities Likely Causes Data Pump Metadata Corruption:

Internal Data Pump packages or objects may be in an inconsistent state. Stale Dictionary Statistics:

Outdated statistics on internal dictionary tables or fixed objects can cause Data Pump to fail during its preparation queries. Invalid Objects: Dependent objects like SYS.KUPW$WORKER SYS.DBMS_METADATA might be invalid. Empty Temporary Tablespace:

If the temporary tablespace is empty or incorrectly configured, internal sort/join operations during import preparation can fail. WordPress.com Recommended Solutions Gather Dictionary Statistics: If the error persists, the dump file is

Refresh internal metadata statistics to ensure the Data Pump worker can execute its internal queries correctly.

EXEC DBMS_STATS.GATHER_DICTIONARY_STATS; EXEC DBMS_STATS.GATHER_FIXED_OBJECTS_STATS; Use code with caution. Copied to clipboard Rebuild Data Pump Utility:

If internal corruption is suspected, reload the Data Pump metadata objects. For 12c and higher: @?/rdbms/admin/dpload.sql (for CDB/PDB environments, ensure PDBs are open). For older versions (10g/11g): @?/rdbms/admin/catdp.sql @?/rdbms/admin/catmetx.sql Check for Invalid Objects: Ensure all objects are valid. owner, object_name, object_type dba_objects Use code with caution. Copied to clipboard Recompile any invalid objects using the @?/rdbms/admin/utlrp.sql Verify Temporary Tablespace:

Ensure the database has a functioning default temporary tablespace with datafiles attached. tablespace_name dba_temp_files; Use code with caution. Copied to clipboard Exclude Statistics during Import:

Sometimes the error is triggered by the import of statistics themselves. Try adding EXCLUDE=STATISTICS

command and gather them manually after the import completes. WordPress.com If these steps do not resolve the issue, check the trace files generated in the directory for a more specific error code (like ) following the ORA-39126 message. Oracle Communities Are you running this import on a Multitenant (CDB/PDB) architecture or a

Primary Causes

| Cause | Description | |-------|-------------| | Corrupt dump file | File transfer errors (binary vs. ASCII), incomplete dump, or storage corruption | | Character set mismatch | Source and target databases have incompatible character sets, especially with NCLOB/NVARCHAR2 | | Invalid table definition | Table on target has columns that conflict with dump file (data type, length, partition differences) | | Object already exists | Table exists but with constraints/triggers that block Data Pump transformation | | Oracle Bug | Known issues in specific versions (especially 11.2, 12.1, 18c, and early 19c) | | Insufficient privileges | Worker cannot perform a required operation due to missing grants | return to the export step:

The Night the Data Pipeline Broke

The clock on the wall read 2:14 AM. Outside the server room, the city was asleep, but inside, the air conditioning hummed a monotonous drone. Arthur, the lead DBA, was running the final migration script for the company’s new CRM system. The stakeholder meeting was at 8:00 AM, and the data pump import job was at 94%.

"Almost there," Arthur whispered, watching the terminal scroll with satisfying speed. Rows were being processed, indexes were building. He reached for his cold coffee, ready to celebrate a smooth deployment.

Then, the scrolling stopped.

It didn’t stop with a gentle "Job completed" message. It stopped with a violent, jagged block of text that turned his stomach into a knot.

ORA-39126: Worker unexpected fatal error in KUPW$WORKER.PREPARE_DATA_IMP

Arthur froze. The error code ORA-39126 was generic, a catch-all for "something terrible happened inside a Data Pump worker process." The specific location—KUPW$WORKER.PREPARE_DATA_IMP—told him the failure happened during the data preparation phase. The job wasn't just paused; it was dead.

He scrambled to check the log file, his fingers shaking slightly over the keyboard.

5. Check target table structure

Compare source and target table definitions (columns, data types, partitions). Use SQLFILE parameter to extract DDL from dump:

impdp ... SQLFILE=create_tables.sql

Step 8: Recreate the Dump File

If all else fails, return to the export step: