"no healthy upstream" error when attempting to access the vCenter Server vSphere Client

Products

• VMware vCenter Server

Issue/Introduction

• Logging in to the vCenter Server using the vSphere Client fails.
• The following error is observed when trying to access the vCenter Server via FQDN from a web browser:
  
  no healthy upstream
  
  

 

• In certain situations, you will get the "no healthy upstream" error immediately after clicking on "Launch vSphere Client":
  
  

 

• The error message is observed while redirecting to "websso" page:
  
  

Cause

This issue may occur due to a number of reasons, such as:

• The VPXD service on the vCenter Server is not running or not accepting connections due to:
  • Expired certificates
  • Disk space issues.
  • Running out of sessions (reached the maximum limit of 2000)
  • The service running out of memory
  • Scheduled maintenance, such as updates.
• The SSO service (vmware-stsd) is down or not responding due to:
  • The service running out of memory
  • Scheduled maintenance, etc.
• The file /etc/hosts has been modified from its default configuration, preventing services from starting.

Resolution

Before troubleshooting, it is critical to understand what a "no healthy upstream" error means. "no_healthy_upstream" is an alternate error message for HTTP Return code 503, which indicates that the server is temporarily unable to handle the request.

 

To verify if a "no healthy upstream" error is being caused by expired certificates, please use the steps in the following KB article to verify the certificate expiration dates on the vCenter Server:

• Verify and resolve expired vCenter Server certificates using command line interface

 

To renew/regenerate the self-signed certificates on a vCenter Server, please use the Certificate Manager utility on the vCenter Server using the steps detailed in the following KB article:

• Regenerate vSphere 6.x, 7.x, and 8.0 certificates using self-signed VMCA