“No Healthy Upstream” Error When Accessing vSphere Client in vCenter Server Due to Datastore Space Constraints

Products

• VMware vCenter Server

Issue/Introduction

• Logging into vCenter Server via the vSphere Client fails. When navigating to the vCenter FQDN or IP in a web browser, users encounter: “no healthy upstream”
• This message corresponds to HTTP 503—indicating that the server cannot currently handle the request.
  
  
  
  
  

Note: Certificate validation is not the cause here—Machine SSL, STS, and Root certificates are confirmed valid and unexpired.

Environment

vCenter Server 7.X

vCenter Server 8.X

Cause

The Photon OS based virtual appliance enters emergency mode.

 

The vCenter Server appliance VM console:

The appliance fails to start, and there is an error similar to:

[FAILED] Failed to start File System Check on /dev/disk...uuid/#####-### See 'systemctl status systemd-fsck-root.service' for details.

[DEPEND] Dependency failed for /sysroot.

[DEPEND] Dependency failed for Initrd Root File System.

[DEPEND] Dependency failed for Reload Configuration from the Real Root.

 

Datastore Full or Disk Issues:

Validation:

• Log in to the ESXi Host Client: In the ESXi Host Client interface, locate and click on "Storage" in the left-hand navigation pane.
• Select the Datastore: In the Storage view, you will see a list of datastores configured on the ESXi host. Click on the specific datastore you want to check.
• View Datastore Details: Once you select a datastore, the right-hand pane will display its details. Look for information related to "Capacity," "Free Space," and "Used Space." 
  These metrics will indicate the total size of the datastore, the available free space, and the amount of space currently in use.
  
  
• If the datastore hosting the vCenter VM is full—or file systems under Photon OS are corrupted—the appliance may boot into emergency mode.

Resolution

Address Datastore Full / Emergency Mode Situations

1. Expand Datastore Capacity:

• Power off the vCenter VM.
• On the ESXi host, increase the datastore capacity (e.g., via SAN expansion).
• Expand the datastore by following the document below.
  Increase Capacity of vSphere VMFS Datastore
  
• Confirm the datastore now shows free space.

 

Important: Take a snapshot of the vCenter VM before performing file-system repairs.

2. Boot into Emergency or Perform Auto‑fsck

• Reboot the vCenter appliance VM.
• At the GRUB menu, press e quickly when the Photon OS splash screen appears.
• Locate the linux kernel line and append either fsck.repair=yes (to auto-fix filesystem inconsistencies) or systemd.unit=emergency.target (to manually run fsck). Press F10 to boot.

or

• Once fsck completes, power off and then power on the appliance.