NSX Manager UI stops responding and returns HTTP ERROR 503

Products

• VMware NSX

Issue/Introduction

• NSX manager UI does load and returns error similar to below.
  This page isn’t working right now
nsxmgr.corp.local  can't currently handle this request
• The cluster remains healthy when checked from CLI using get cluster status command.
• The  /var/log/proxy/envoy_access_log.txt shows logs similar to bleow
  [2026-02-04T12:49:08.190Z] 10.x.x.x 10.y.y.y.y "GET" "/api/v1/transport-nodes/c7b3####-2856-####-ba92-3763####e83b/network/interfaces/vmnic1/stats" "HTTP/1.1" 503 UAEX 0 0 60003 - "10.x.x.x" "Apache-HttpClient/4.5.9 (Java/17.0.10)" "7002####-a84b-####-823d-5dac####ed09" "10.y.y.y:443" "-"
[2026-02-04T12:49:08.233Z] 10.x.x.x.x 10.y.y.y.y "GET" "/api/v1/transport-nodes/8c84####-266d-####-98d0-35ce####73ed/network/interfaces/vmnic2/stats" "HTTP/1.1" 503 UAEX 0 0 60004 - "10.x.x.x.x" "Apache-HttpClient/4.5.9 (Java/17.0.10)" "83a1####-2a97-####-aa53-2e52####702e" "10.y.y.y:443" "-"

Environment

NSX 4.2.2.x and lower

Cause

The issue stems from a vIDM/LDAP connection failure coupled with the fact that the older versions of NSX lack a timeout configuration in the HTTPClient. Consequently, these connection threads become stuck and block new threads, resulting in the reported service disruption.

Resolution

The issue is resolved in NSX 4.2.3 and NSX 9.0.1 and later releases.

Workaround:
Restart the auth service. Login into the NSX manager as admin user and run: 
restart service auth