Logging into VMware vCenter Server shows the following warning message/banner : "Your environment is now in mixed mode. It is recommended you update your linked vCenter Servers to the same version"

Products

• VMware vCenter Server

Issue/Introduction

• vCenter System Configuration topology shows all vCenter Servers are on the same version:

• This Issue may occur in standalone vCenter Servers as well

Environment

VMware vCenter Server 7.0.x
VMware vCenter Server 8.0.x

Cause

This issue can occur if there are stale vCenter entries in lookupservice registration, or nodes that have not been upgraded yet in linked mode.

Resolution

Caution: This procedure involves data modification on vCenter Server Appliance. Ensure you have valid backup of all vCenter Servers in replication partnership. If you are taking a snapshot before the change, all vCenters in replication partnership with the vCenter where the change is made need to be powered off at the same time to take a consistent snapshot state of the vCenter.

To resolve this issue, find the stale registration and unregister it from lookupservice:

1. login to VCSA using SSH with root credentials
2. Run the following command to get the service registrations. 

/usr/lib/vmware-lookupsvc/tools/lstool.py list --url https://localhost/lookupservice/sdk --type vcenterserver > /tmp/psc.txt --no-check-cert

3. use less/vi to open /tmp/psc.txt to review presence of any stale registration

Sample lstool output section for vCenter registration may look like: 

Name: AboutInfo.vpx.name
        Description: AboutInfo.vpx.name
        Service Product: com.vmware.cis
        Service Type: vcenterserver
        Service ID: default-first-site:3c80e5dd-####-####-####-########378
        Site ID: default-site
        Node ID: 12833276-####-####-####-########242
        Owner ID: vpxd-f376af08-####-####-####-########[email protected]
        Version: 5.1
        Endpoints:

 Name: AboutInfo.vpx.name
        Description: AboutInfo.vpx.name
        Service Product: com.vmware.cis
        Service Type: vcenterserver
        Service ID: abd2e86e-####-####-####-########2e1
        Site ID: default-first-site
        Node ID: d4b8027e-####-####-####-########5e7
        Owner ID: vpxd-9a77086d-####-####-####-########[email protected]
        Version: 7.0
        Endpoints:

Name: AboutInfo.vpx.name
        Description: AboutInfo.vpx.name
        Service Product: com.vmware.cis
        Service Type: vcenterserver
        Service ID: 218df911-####-####-####-########876
        Site ID: default-site
        Node ID: 12833276-####-####-####-########242
        Owner ID: vpxd-f376af08-####-####-####-########[email protected]
        Version: 7.0

4. From the output if you see a stale registration, note down the Service ID

In this example: default-first-site:3c80e5dd-####-####-####-########378

5. Remove the old service registration using the below command. 

/usr/lib/vmware-lookupsvc/tools/lstool.py unregister --url https://localhost/lookupservice/sdk --id default-first-site:3c80e5dd-####-####-####-########378 --user '[email protected]' --password '<password>' --no-check-cert

6. Re-login to the Web Client. 

Note: This is only intended to remove stale vCenter service registrations. For vCenter registrations in linked mode that have not yet been upgraded, those should be upgraded and not removed using the commands above.