After application upgrade or move Ranger or DB, account used for VC authentication is locked. Sometimes, Windows account/accounts used for repo authentication may be locked.
As soon as you open Ranger GUI, re-authenitcate VC/ESX/repo.
Unfortunately, in few cases it was not possible to re-authenticate VC - account was locked while GUI was opening. Workaround is to mark VC as deleted in Ranger DB (set IsDeleted column to 1for VC record in InventorySourceConnection table). Gui opens without VC in inventory. If you add VC, existing record will be re-used.