HCX vCenter Plugin Fails with Error: Http failure response

Products

• VMware HCX

Issue/Introduction

When attempting to launch the VMware HCX plugin from within the vSphere Client, the interface fails to load and displays the following error:

Http failure response for https://<vcenter-fqdn>/ui/hcx/hcx-ui/rest/hybridity/api/sessions: 401 OK or 500 OK

Environment

• Product: VMware HCX
• Component: HCX vCenter Plugin
• Versions: HCX 4.x and later

Cause

The service account used for vCenter Server Registration in the HCX Manager does not have sufficient permissions. Specifically:

1. The account is not a member of the local vSphere administration group (e.g., [email protected]).
2. The account lacks the Administrator role at the global level.

HCX plugin not working in vCenter UI, Error "Http failure response 401 OK"

Resolution

To resolve this issue, ensure the service account used by HCX has the mandatory prerequisites for plugin registration:

1. Log in to the vSphere Client with an administrative account.
2. Navigate to Administration > Single Sign-On > Users and Groups.
3. Locate the service account used for HCX registration.
4. Add this account to the Administrators group (typically [email protected]).
5. Navigate to Administration > Access Control > Global Permissions.
6. Ensure the service account is assigned the Administrator role.
7. Log in to the HCX Appliance Management Interface (https://<HCX-Manager-IP>:9443).
8. Navigate to Configuration > vCenter Server and click Edit to verify or re-enter the credentials for the updated service account.
9. Restart the vSphere Client services or re-login to the vSphere UI to verify the plugin functionality.