All Replicat installations should be upgraded at the same time. It is critical to ensure that all trails leading to all Replicat groups on all target systems are processed until empty, according to the upgrade instructions.

When upgrading from releases prior to 19c release of Oracle GoldenGate, ensure that you do not use the SOURCEDEF parameter in Replicat, otherwise the Replicat will abend. However, if the trail file format is pre-12.2, then SOURCEDEF is still required because no metadata exists in the trail file.

Because the TIMEZONE datatype is managed differently with Oracle GoldenGate 21c, you may need to run the ALTER REPLICAT extseqno command to synchronize with newer trail files after consuming the old trail file written by the Extract.