OVF or OVA Export Fails with "Operation Timed Out" after few hours in vSphere Client

Products

• VMware vSphere ESXi

Issue/Introduction

• Exporting a large virtual machine as an OVF or OVA template via the vSphere Client fails consistently after approximately 4 hours.
• The download progress may reach a high percentage (e.g., 50-80%) before failing with the error: "Operation timed out."
• Manual file transfers via WinSCP or browser-based datastore downloads appear incomplete or corrupted.
• Smaller VMs export successfully without issue.

Environment

VMware vCenter Server 8.x

Cause

The failure is typically caused by two distinct timeout mechanisms:

1. vSphere Client Internal Timeout: The vSphere UI has a default hard-coded timeout of 14,400,000 milliseconds (4 hours). If the browser does not complete the file stream within this window, the session is terminated.
2. HttpNfcLease Expiration: vCenter Server renews the Network File Copy (NFC) lease every 20 minutes. In environments with slow throughput or extremely large disks, if vpxa does not detect sufficient progress, the lease expires, causing the backend task to fail.

Resolution

To resolve this issue, you must extend the timeout parameters in the vCenter Server configuration.

Prerequisites

• Take a snapshot of the vCenter Server Appliance (VCSA) before making changes.
• Ensure you have root SSH access to the VCSA.

Step 1: Increase vCenter Advanced Settings (NFC Timeouts)

1. Log in to the vSphere Client.
2. Select the vCenter Server object in the inventory.
3. Navigate to Configure > Advanced Settings > Edit Settings.
4. Add or update the following parameters:
   • config.httpNfcTicket.timeoutPeriodMinute : 60
   • config.httpNfcTicket.renewalPeriod : 3600
5. Click Save.

Step 2: Increase vSphere UI Download Timeout

1. SSH into the vCenter Server as root.
2. Navigate to the directory: /etc/vmware/vsphere-ui/.
3. Back up the properties file:

   cp webclient.properties webclient.properties.bak

4. Edit webclient.properties using vi:

   vi webclient.properties

5. Locate ovf.download.timeout (or add it if missing) and increase the value. For an 8-hour timeout:

   ovf.download.timeout=28800000

6. Restart the vSphere Client service:

   service-control --restart vsphere-ui

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Workaround

Use the OVF Tool (Command Line): The VMware OVF Tool is a command-line utility that is significantly more resilient for large transfers. It bypasses browser-based session limits and handles network fluctuations more gracefully.

Example Export Command:

ovftool --noSSLVerify "vi://<user>@<vcenter_fqdn>/<datacenter_name>/vm/<vm_name>" C:\Exports\<vm_name>.ova

Additional Information

• Related KB 318566: Exporting a VM as OVF template to content library or deploying a VM from OVF library item results in timeout error.
• Related KB 413289: When exporting OVF from vSphere Client takes more than 4 hours, task fails with timeout.