ORA-16012: Archivelog standby database identifier mismatch

Check the following list of possible issues.
If any of the following conditions exist, redo transport services will fail to transmit redo data to the standby database:

1. The service name for the standby instance is not configured correctly in the tnsnames.ora file for the primary database.
2. The Oracle Net service name specified by the LOG_ARCHIVE_DEST_n parameter for the primary database is incorrect.
3. The LOG_ARCHIVE_DEST_STATE_n parameter for the standby database is not set to the value ENABLE.
4. The listener.ora file has not been configured correctly for the standby database.
5. The listener is not started at the standby site.
6. The standby instance is not started.
7. You have added a standby archiving destination to the primary SPFILE or text initialization parameter file, but have not yet enabled the change.
8. Redo transport authentication has not been configured properly. See section 3.1.2 for redo transport authentication configuration requirements.
9. You used an invalid backup as the basis for the standby database (i.e. , you used a backup from the wrong database, or did not create the standby control file using the correct method).