If you vCenter is showing as in error state in sddc manager during precheck or when your trying to upgrade VCF. If you believe there is no issue you can update the sddc manager db from error to active by doing the following. Snapshot your sddc manager first
ssh to sddc manager via vcf account and switch to su, get the id when running the commands
psql -h localhost -U postgres
\c platform
select * from vcenter;
update vcenter set status = 'ACTIVE' where id = 'ffe6279d-d681-45ac-846a-a58505a7f25b'