You see the below symptoms when vCenter Server is configured to use the embedded vPostgres database.
Please ensure extensions are compatible with the new vCenter Server and re-register extensions with the new vCenter Server after upgrade.Please refer to the vSphere documentation on extensions, and the upgrade and interoperability guides.Error: Error while reading data from the vCenter Server database: psql: FATAL: password authentication failed for user "postgres"
VMware vCenter Server 6.5.x
This issue occurs due to incorrect password information for postgres user in the %appdata%\postgresql\pgpass.conf file.