VPC Subnet has Failed status reporting "Unable to connect to vCenter"

Products

• VMware NSX

Issue/Introduction

• On the NSX UI, VPCs > Virtual Private Clouds > Subnets, click Subnets count which opens the Set Subnets window where subnets have a Failed status
• Clicking on "Failed" shows a Realization Error:
  
  Realization Errors : <>
Unable to realize folder <> for LogicalSwitch LogicalSwitch/<UUID> under parent Folder vmware-system-supervisor-services-vpc_<UUID> in VC <UUID>. Unable to connect to vCenter.
 
• On the NSX UI, System > Fabric > Compute Managers, Compute Manager Connection Status is Up
• Login to vCenter on the vSphere Client is not working and does not complete

Environment

VMware NSX 9.0

Cause

This error can occur when vCenter has an issue with credential validation which impacts the NSX system user.

Resolution

This issue has been observed when encountering the following known issue, Getting following error "An error occurred while fetching identity providers. Please try again later. If the problem persists, contact your administrator" when logging in with domain users on vCenter Server 9.0.

It is possible the same symptoms may be observed in NSX for other issues that are impacting vCenter connectivity or authentication.