Vcenter Server 5.5 Certificate Expired Jun 2026

| Error Message | Likely Cause | Solution | | :--- | :--- | :--- | | “STS signature invalid” | Solution User cert (STS) expired | Run certificate-manager → Option 2 | | “503 Service Unavailable” | Web services trust broken | Check vmware-sts-idp logs; replace STS certs | | “Peer certificate expired” (vMotion) | ESXi host cert expired | Generate new host certificates via Host Profile or CLI ( /sbin/generate-certificates ) | | “The RPC server is unavailable” | SSL handshake fails on port 443 | Verify firewall rules; replace SSL cert on vCenter | | “Certificate chain not trusted” | Missing Root CA on client | Install vCenter’s new root cert into client’s Trusted Store |

An expired certificate in vCenter Server 5.5 is not a death sentence for your virtual infrastructure, but it is a serious incident. By systematically regenerating the Machine SSL certificate and the STS token certificate, you can restore full functionality within an hour. However, the repeated need to perform these manual steps underscores the age and fragility of vCenter 5.5. Treat this event as the final warning: plan your migration to a modern vCenter version immediately, where certificate lifecycle management is no longer your problem to solve manually. vcenter server 5.5 certificate expired

have their own certificate stores. If these are expired, you'll see "Failed to connect" errors even after fixing the main vCenter service. You may need to use the SSO Certificate Tool provided by VMware (Broadcom) to update these components. Summary Checklist Backup your vCenter Server (Snapshot or VM backup). | Error Message | Likely Cause | Solution