vCenter server upgrade pre-upgrade check fails with "This operation is not allowed in the current state as operation 'None' is already in progress"

Products

• VMware vCenter Server
• VMware vCenter Server 8.0

Issue/Introduction

• Upgrading vCenter Server from 7.x to 8.x fails with the error message :
  
  Pre-upgrade check failed due the following problem: This operation is not allowed in the current state as operation 'None' is already in progress
  
  
  
  
• In the applmgmt logs (/var/log/vmware/applmgmt/applmgmt.log) of the newly deployed vCenter 8.x appliance, repeated timeout errors are observed, indicating that required files cannot be downloaded over port 443.
• Following snippets were also found in the location: /var/log/vmware/upgrade/upgraderunner.log

YYYY-MM-DDThh:mm:ss.Z WARNING proxy got Failed to download /tmp/vmware-root_1791-2125937827/exec-vmware129-stdout from https://<FQDN_OF_ESXI_HOST>:443/guestFile?id=4&token=52####0df-d##8-4##a-#6e#-0f9####217##4: [Errno 110] Connection timed out, retrying ...
2025-08-07T18:19:07.642Z ERROR transport.guestops Failed to download from https://<FQDN_OF_ESXI_HOST>:443/guestFile?id=4&token=52####0df-d##8-4##a-#6e#-0f9####217##4: [Errno 110] Connection timed out
Traceback (most recent call last):
  File "/usr/lib/python3.10/socket.py", line 833, in create_connection
    sock.connect(sa)
TimeoutError: [Errno 110] Connection timed out

During handling of the above exception, another exception occurred:

Traceback (most recent call last):
 
  File "/usr/lib/python3.10/urllib/request.py", line 1351, in do_open
    raise URLError(err)
urllib.error.URLError: <urlopen error [Errno 110] Connection timed out>
YYYY-MM-DDThh:mm:ss.Z  WARNING proxy got Failed to download /tmp/vmware-root_1791-2125937827/exec-vmware129-stdout from https://<FQDN_OF_ESXI_HOST>:443/guestFile?id=4&token=52####0df-d##8-4##a-#6e#-0f9####217##4: [Errno 110] Connection timed out, retrying ...
YYYY-MM-DDThh:mm:ss.Z  WARNING transport.guestops Failed to get intermidate output for process 21487 on target ##.##.##.##: Failed to download /tmp/vmware-root_1791-2125937827/exec-vmware121-stdout from ##.##.##.6##: An error occurred while communicating with the remote host.
YYYY-MM-DDThh:mm:ss.Z ERROR upgrade_commands Could not establish connection to source host (//<FQDN_OF_ESXI_HOST:443) or source vCSA (<FQDN_OF VCENTER_SERVER>)
YYYY-MM-DDThh:mm:ss.Z ERROR root Could not create command factory.
YYYY-MM-DDThh:mm:ss.Z ERROR __main__ ERROR: Fatal error during upgrade REQUIREMENTS. For more details take a look at: /var/log/vmware/upgrade/requirements-upgrade-runner.log
YYYY-MM-DDThh:mm:ss.Z INFO root Exiting with exit-code 1

• Additionally, testing connectivity from the new vCenter Server temporary IP to the ESXi host confirms that port 443 is blocked:

          root_localhost# curl -v telnet:///<FQDN_ESXI_HOST>:443/
          *  Trying <FQDN_ESXI_HOST>:443...
          *  Connect to <FQDN_ESXI_HOST> port 443 failed: Connection timed out

Environment

VMware vCenter Server 7.x

VMware vCenter Server 8.x

Cause

This issue occurs when there is a connectivity issue or firewall restrictions between the new vCenter Server and the ESXi host hosting the Source vCenter Server.

Resolution

Involve network/firewall team to validate connectivity and update firewall ACLs to allow HTTPS (port 443) communication between Source vCenter Server, Destination vCenter Server (new appliance) and ESXi host hosting the source vCenter Server.

If ESXi host firewall is configured, Add the Temporary  IP of the new appliance in the Firewall of the ESXI host

• Reference:- Add Allowed IP Addresses for an ESXi Host by Using the VMware Host Client

Additional Information

vSphere 8.0 Documentation – Ports required for upgrading the vCenter Server Appliance