If you see the following error in the alert log of the new primary server during a switchover, that's normal. It's a transient one. ******************************************************************** Fatal NI connect error 12514, connecting to: (DESCRIPTION=(ADDRESS_LIST=(ADDRESS=(PROTOCOL=TCP)(Host=OL6DB01)(Port=1521)))(CONNECT_DATA=(SERVICE_NAME=PROD1)(CID=(PROGRAM=oracle)(HOST=ol7db02)(USER=oracle)))) VERSION INFORMATION: TNS for Linux: Version 12.1.0.2.0 - Production TCP/IP NT Protocol Adapter for Linux: Version 12.1.0.2.0 - Production Time: 30-OCT-2020 15:08:40 … Continue reading Fatal NI connect error 12514 and TNS-12564 →