UI hangs or freezes during migration wizard selection on HCX

Products

• VMware HCX

Issue/Introduction

• The VMware HCX Manager UI frequently hangs, freezes, feels sluggish or times out.
• The issue is most noticeable when using the migration wizard to select virtual machines (VMs).
• Other tabs, such as the Service Mesh tab, may also exhibit significant slowness.
• Despite the UI hangs, backend API responses (as seen in HAR files) appear to be fast and healthy.

Environment

• Product: VMware HCX
• Versions: 9.x (specifically observed on 9.0.2)
• Access Method: Browser-based UI (HCX Manager / Cloud Manager)

Cause

The issue is typically client-side and related to the browser. Diagnostic analysis of HCX logs and browser HAR files often shows that the HCX API is responding within normal thresholds, but the browser is failing to render the data or is getting stuck due to cached data or local browser constraints.

Resolution

To resolve the UI slowness and unresponsiveness, perform the following steps:

1. Clear the browser cache, cookies, and site data for the specific HCX Manager URL.
2. Test the HCX UI in an alternative browser (e.g., switch from Chrome to Firefox or Edge) to rule out browser-specific rendering issues.
3. Temporarily disable browser extensions or plugins that may interfere with JavaScript execution.
4. If the issue persists, verify that the client machine has sufficient local CPU/Memory resources to render large inventory lists.