Uninstalling NSX-T from a host fails due to the host still being a member group: NSGroup with TransportNode for CPU Mem Threshold

Products

• VMware NSX

Issue/Introduction

Symptoms:

• You recently migrated from NSX for vSphere to NSX-T.
• The NSX-T version is less than 3.2.1.
• Your ESXi version is 7.x
• You are trying to uninstall NSX-T from a host.
• Ar error is seen in the UI with the following text:
  • Feb 22, 2022, 10:25:03 AM : Failed to remove NSX on the cluster: Cannot perform Remove NSX on cluster because of following validation errors on transport nodes - 1)4e861f42-aaeb-####-####-####-########e4a: One or more relationships exist for object with id TransportNode/4e861f42-aaeb-####-####-####-########e4a from NSGroup/15fb9ef1-da18-####-####-####-########774. 2)aabb1f42-85c3-####-####-####-########ce1: One or more relationships exist for object with id TransportNode/aabb1f42-85c3-####-####-####-########ce1 from NSGroup/15fb9ef1-da18-####-####-####-########774. 3)4cdb1f42-4dd6-####-####-####-########bf4: One or more relationships exist for object with id TransportNode/4cdb1f42-4dd6-####-####-####-########bf4 from NSGroup/15fb9ef1-da18-####-####-####-########774.

• In the NSX-T manager log /var/log/proton/nsxapi.log:
  • 2022-02-22T10:26:57.981Z ERROR http-nio-127.0.0.1-7440-exec-2 NsxComputeCollectionServiceImpl 8672 FABRIC [nsx@6876 comp="nsx-manager" errorCode="PM26907" level="ERROR" reqId="26de7333-f770-####-####-####-########ed3c" subcomp="manager" username="admin"] Cannot perform Remove NSX on cluster 2a578b1c-49f6-####-####-####-########c6d:domain-c34811 because of following validation errors on transport nodes - 1)4e861f42-aaeb-####-####-####-########e4a : One or more relationships exist for object with id TransportNode/4e861f42-aaeb-####-####-####-########e4a from NSGroup/15fb9ef1-da18-####-####-####-########774. 2)aabb1f42-85c3-####-####-####-########ce1: One or more relationships exist for object with id TransportNode/aabb1f42-85c3-####-####-####-########ce1 from NSGroup/15fb9ef1-da18-####-####-####-########774. 3)4cdb1f42-4dd6-####-####-####-########fbf4 : One or more relationships exist for object with id TransportNode/4cdb1f42-4dd6-####-####-####-########bf4 from NSGroup/15fb9ef1-da18-####-####-####-########774.

Environment

VMware NSX-T

Cause

During the v2T migration, the ESXi hosts are added to a group created by NSX-T called:
NSGroup with TransportNode for CPU Mem Threshold

This group ensures that the transport nodes have the correct CPU memory threshold settings in NSX-T.
As this host is part of the group, it prevents the VIBs from being removed until the host is removed from the group.
This issue is outlined in the NSX-T migration guide as a warning that you should remove it from the group before trying to remove NSX-T from a host that was migrated.
https://docs.vmware.com/en/VMware-NSX-T-Data-Center/3.2/migration/GUID-CEA71E88-F7DF-444B-ACD6-DF20DB1D5674.html

Resolution

From NSX-T 3.2.1 onwards, there is no longer a need to remove the transport node from this group prior to uninstall of NSX-T from the host.

Workaround:
Before removing a host, which was migrated from NSX for vSphere to NSX-T, you need to remove the host from the group: NSGroup with TransportNode for CPU Mem Threshold
Please review the following guide for more details:
https://docs.vmware.com/en/VMware-NSX-T-Data-Center/3.2/migration/GUID-CEA71E88-F7DF-444B-ACD6-DF20DB1D5674.html