Symptoms:
When initiating SDDC Manager upgrade pre-checks from either VCF Operations (Build > Lifecycle > VCF Instances > SDDC Manager Upgrades tab) or the SDDC Manager UI (Lifecycle Management > SDDC Manager > Available Upgrades tab), the operation fails. The following error is displayed in the UI:
`Triggering SDDC Manager upgrade bundle failed. A problem has occurred on the server. Please retry or contact the service provider and provide the reference token`
VMware SDDC 9.1
This issue is resolved in the SDDC 9.1.1 release.