Attempting a vSphere Windows 6.5U3 -> VCSA 6.7U3. Everything is fine until Update Manager attempts to start. (Note: Uninstalled 6.5 Update Manager and removed the extension from existing environment.)
Found the following errors in the logs but am unable to find any KB or other information on them:
2020-11-16T18:55:29.315Z UpdateMgr firstboot failed
2020-11-16T18:55:29.315Z Update Manager exception details [<cis.l10n.LocalizableMessage object at 0x7f204a9edc18>]
[2020-11-16 18:55:29,072 INFO] Found VC(https://hostname:443/sdk )
[2020-11-16 18:55:29,180 INFO] Updating VUM extension with VC
[2020-11-16 18:55:29,205 ERROR] Exception raised while refreshing the certs. err: local variable 'ret' referenced before assignment
look at this to check what is supported or not.