Ora-39126 Worker Unexpected Fatal Error In Kupw-worker.prepare-data-imp 71 !!hot!! May 2026

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

: The internal packages or views used by Data Pump may be invalid or corrupted. Missing or Incorrect Tablespaces The error ORA-39126: Worker unexpected fatal error in

Then import that table separately with additional diagnostic parameters: ORA-39126 : Indicates an unexpected fatal error in

Empty Temporary Tablespace: While less common for code [71], an empty or incorrectly configured default temporary tablespace can trigger ORA-39126. Recommended Resolutions 1. Rebuild Data Pump Catalog converting data types

, refers to a specific internal line or code path within the KUPW$WORKER

2. Data Type Mismatch or Conversion Failure

When importing into a target table with a different definition than the source:

Conclusion

• ORA-39126: Indicates an unexpected fatal error in a Data Pump worker process.
• KUPW-WORKER: Kernel Utility Process Worker – the background process handling Data Pump execution.
• PREPARE-DATA-IMP: The phase where the import worker prepares to load data into a table (e.g., parsing data, converting data types, allocating buffers, handling LOBs/XMLTypes).
• [71]: This number often refers to a specific internal sub-component or error context. In many Oracle versions, code 71 relates to issues with spatial data, XML schema validation, or row processing failures. However, it can also be a generic pointer to a failure during data preparation.