VM Backup Fails in Veeam with Error "DiskLib error: [13].The file is locked or in use -- File open failed: File not open"

Products

• VMware vSphere ESXi

Issue/Introduction

• VM backup initiated via Veeam fails with the following error:
  Error: DiskLib error: [13].The file is locked or in use -- File open failed: File not open


• This issue occurs only when the backup is initiated on a specific ESXi host. However, backup for the same VM works successfully when initiated from a different host.
• When triggering the backup, the Veeam job fails with the error message:

VM owner: XXXX
Getting VM info from vSphere
Error: DiskLib error: [13].The file is locked or in use -- File open failed: File not open Failed to create N ...
Processing finished with errors at Error: DiskLib error: [13].The file is locked or in use -- File open failed: File not open
Failed to create NFC download stream. NFC path: [nfc://conn:XXX.XX.XX.X,nfchost:host-XXXXX,stg:datastore-XXXX@XXXX-01-XXXX/XXXX-01-XXXX.vmx].
Agent failed to process method {Transfer.FileToText).

 

Cause

The Veeam proxy is unable to reach the ESXi host over the network. As a result, the backup request never reaches the ESXi host, and there are no corresponding logs or backup tasks initiated from the ESXi side.

Supporting observations:

• Packet capture reveals no traffic from the Veeam server to the ESXi host.

• No errors are reported in the ESXi host logs.

Resolution

 

• Verify Network Connectivity

  • Check if the Veeam backup proxy has proper network connectivity to the affected ESXi host.

  • Ensure there are no firewall rules or network ACLs blocking traffic between the Veeam proxy and the ESXi host.

• Validate Veeam Proxy Configuration

  • Make sure the correct proxy is selected for the job.

  • Verify that the proxy has access to the required network segment and ESXi host.

• Contact Veeam Support

  • If connectivity and configuration are verified but the issue persists, contact Veeam support for deeper troubleshooting.