Problem Description

When attempting to back up or manage a Proxmox virtual machine (VM)—particularly following a recent VM restore operation—the following symptoms may occur:

Backup jobs for a specific Proxmox VM fail consistently.
Attempts to delete existing Druva backup snapshots from the Proxmox VE UI or command-line interface (CLI) fail.
Backup job logs report an internal error with ErrorCode: 1001.

Cause

This issue occurs when a Proxmox VM has locked or corrupted snapshots.

If a VM remains in a locked state (commonly caused by an interrupted process, a failed cleanup, or a recent restore operation), Proxmox VE prevents any subsequent modifications to the VM's disk state. Consequently, Druva cannot purge old recovery points or process snapshot creation, resulting in backup failure.

Traceback

In the Druva progress logs, the backup job terminates with the following error:

Job cancelled Marking job done. Job done marked. Done state: . Errors encountered: ErrorCode: 1001, ErrorMessage: Internal error. Error encountered: ErrorCode: 1001, ErrorMessage: Internal error.

Preceding log entries may show snapshots being created and initial full backup uploads starting before the job eventually hangs or cancels:

YYYY-MM-DD HH:MM:SS  Snapshot started YYYY-MM-DD HH:MM:SS  Snapshot created: druva-backup-<VM_ID>-<TIMESTAMP> YYYY-MM-DD HH:MM:SS  Proceeding with full backup YYYY-MM-DD HH:MM:SS  Estimation for Backup completed, Total Size: <SIZE>. YYYY-MM-DD HH:MM:SS  Starting upload

Resolution

To resolve this issue, manually clear the VM lock in Proxmox VE and remove problematic snapshots before triggering a new backup.

Step 1: Check and Remove VM Locks in Proxmox

Log in to the Proxmox VE web interface or connect via SSH to the Proxmox node hosting the affected VM.
Identify the VMID by running:
```
qm list
```
Check if the VM is currently locked:
```
qm status <VM_ID> --verbose
```
If a lock is present (e.g., lock: backup or lock: snapshot), clear the lock:
```
qm unlock <VM_ID>
```

Step 2: Delete Corrupted or Stale Snapshots

In the Proxmox VE web interface, navigate to VM > Snapshots.
Locate old, stale, or corrupted Druva snapshots (typically formatted as druva-backup-<VM_ID>-<TIMESTAMP>).
Select the problematic snapshot(s) and click Remove.
Alternative via CLI: If UI removal fails, delete the snapshot using:
```
qm delsnapshot <VM_ID> <SNAPSHOT_NAME>
```

Step 3: Trigger Backup

Open the Druva Management Console.
Run a manual backup for the VM to verify that the job completes successfully.

Verification

To confirm resolution:

Verify via Proxmox CLI that qm status <VM_ID> no longer displays a lock parameter.
Confirm the stale snapshot no longer appears under VM > Snapshots or in qm listsnapshot <VM_ID>.
Verify that the manual backup job completes with status Successful in the Druva Management Console.

Proxmox VM Backups Fail with Error Code 1001 Due to Locked or Corrupted Snapshots