Upgrading VCF Operations from 9.0.2 to 9.1 returns sync error when upgrading ESXi host

Products

• VCF Operations

Issue/Introduction

• Upgraded SDDC manager to 9.1 and also vCenter to 9.1
• VCF operations is on 9.0.x . 
• Reconfiguring the VCF adapter after removing it fails with the error: Failed to create VCF cloud account. Management Domain details is null.
• /storage/log/vcops/log/vcops-bridge.log in VCF operations reports the error : 

  Exception occurred during call to endpoint https://<VCFOPS_FQDN>/v1/domains with Error: Unrecognized field "pageMetadata" (class com.vmware.vrops.adapter.vcf.model.api.v1.domain.Domains), not marked as ignorable (one known property: "elements"])
  at [Source: (String)"{"elements":[{"id":"########-####-####-####-############","name":"<domain>","orgName":"<orgname>","status":"ACTIVE","upgradeState":"AVAILABLE","upgradeStatus":{"status":"READY"},"type":"MANAGEMENT","owners":[[credential]"],"vcenters":[{"id":"########-####-####-####-############","fqdn":"<FQDN>","vcInstanceId":"########-####-####-####-############"}],"vspClusters":[],"ssoId":"########-####-####-####-############","ssoName":"<name>","isManagement"[truncated 2173 chars]; line: 1, column: 2610] (through reference chain: com.vmware.vrops.adapter.vcf.model.api.v1.domain.Domains["pageMetadata"])

Environment

• vCenter 9.1.x
• VCF Operations 9.x
• SDDC manager 9.1.x

Cause

SDDC Manager and vCenter were upgraded to VCF 9.1 but VCF Operations is on 9.0.2. 

Resolution

VCF Operations should be upgraded before upgrading SDDC manager and vCenter.  Refer to documentation Upgrading to VMware Cloud Foundation 9.1