Proxmox VM failed with error: vmname : Failed to perform backup: Failed to clear resources from previous backups

Dear all,

I'm currently encountering an issue with one of our backup jobs affecting approximately seven virtual machines. Each of them fails with the following error:

<vmname> : Failed to perform backup: Failed to clear resources from previous backups  

To troubleshoot, I created a new backup job for one of the affected VMs, but the error persists.

From the log file, the relevant entries are:

2025-07-31 09:31:07.4637 00220 [10420] ERROR | [TaskServiceClientExtensions]: Failed to await the Backup task 2f17d6a2-be43-41b9-bcb5-eddebf091271: Veeam.Communication.TypeProvider.Invoke.RpcCallException: Failed to perform backup: Failed to clear resources from previous backups
2025-07-31 09:31:07.4637 00220 [10420] ERROR | [TaskServiceClientExtensions]:    at VCF.RuntimeAssembly.Proxy.5ba0c407-17f5-4d21-966b-1a42e64ddb07.AwaitTask(Guid)
2025-07-31 09:31:07.4637 00220 [10420] ERROR | [TaskServiceClientExtensions]:    at Veeam.Vbf.Project.Utilities.Extensions.TaskServiceClientExtensions.AwaitTask(ServiceReference serviceReference, Guid taskId, TaskType type)
2025-07-31 09:31:07.4637 00220 [10420] ERROR | [BackupServiceClientExtensions]: Failed to back up the VM "423c71b1-21bd-96c1-70b3-a4977cd292a3:134" using the worker "36a9520d-7ef9-409d-beac-3efe96a1daa0:101": Veeam.Communication.TypeProvider.Invoke.RpcCallException: Failed to perform backup: Failed to clear resources from previous backups
2025-07-31 09:31:07.4637 00220 [10420] ERROR | [BackupServiceClientExtensions]:    at VCF.RuntimeAssembly.Proxy.5ba0c407-17f5-4d21-966b-1a42e64ddb07.AwaitTask(Guid)
2025-07-31 09:31:07.4637 00220 [10420] ERROR | [BackupServiceClientExtensions]:    at Veeam.Vbf.Project.Utilities.Extensions.TaskServiceClientExtensions.AwaitTask(ServiceReference serviceReference, Guid taskId, TaskType type)
2025-07-31 09:31:07.4637 00220 [10420] ERROR | [BackupServiceClientExtensions]:    at Veeam.Vbf.Project.Utilities.Extensions.TaskServiceClientExtensions.WaitForTaskAsync(ExternalServiceClientAbstract client, Guid taskId, BackupRestoreAppSettings appSettings, TaskType type, CancellationToken cancellationToken)
2025-07-31 09:31:07.4637 00220 [10420] ERROR | [BackupServiceClientExtensions]:    at Veeam.PlatformService.BackupRestore.Extensions.BackupServiceClientExtensions.PveBackupVmAsync(ExternalServiceClientAbstract backupService, BackupRestoreAppSettings backupRestoreAppSettings, VmBackupParams backupParams, CancellationToken cancellationToken)

As part of my troubleshooting steps, I have:

• Powered off and restarted the VM

• Verified that the QEMU guest agent is installed and running

Unfortunately, the issue remains unresolved.

Has anyone encountered this error before or have any suggestions on how to proceed?

Thank you for your help.

Best regards,

Yanick