If the import succeeds, run DBMS_STATS.GATHER_SCHEMA_STATS after the data is loaded. 2. Recompile Invalids on Source and Target
Run a check on the target schema before restarting the import:
When PREPARE_DATA_IMP [71] crashes, it is usually because the environment or data definitions violated an underlying database constraint that Data Pump did not filter out. The four most common causes include: If the import succeeds, run DBMS_STATS
Check My Oracle Support for specific bug IDs like 28307854 or 18393005 if your database is on version 12.1 or 12.2, as these have known issues with ORA-39126.
Bugs in specific Oracle versions (often fixed in later Patch Sets). Conflicts with "External Tables" or "Virtual Columns." The four most common causes include: Check My
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.
This guide explores the causes and solutions for this specific failure. Understanding the Error Context The error usually appears in the import log like this: It is the worker process signaling a fundamental
The internal system packages responsible for Data Pump ( WORKER) are invalid or corrupted.