ALTER SYSTEM SET PGA_AGGREGATE_TARGET=2G SCOPE=BOTH;
, it typically points to a failure during the initialization phase of a Data Pump Import ( The Anatomy of the Error ALTER SYSTEM SET PGA_AGGREGATE_TARGET=2G SCOPE=BOTH
Corrupt or invalid KUPW$WORKER or DBMS_METADATA package bodies can prevent the worker from initializing correctly. ALTER SYSTEM SET PGA_AGGREGATE_TARGET=2G SCOPE=BOTH
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. ALTER SYSTEM SET PGA_AGGREGATE_TARGET=2G SCOPE=BOTH