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Azure backup is failing for the system state

Bruce Ollerenshaw 0 Reputation points
2026-06-02T15:24:21.5866667+00:00

Azure backup system state is failing for one Server 2019 VM. Other similar VMs are fine.

Windows for business | Windows Server | User experience | Other
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  1. Harry Phan 21,095 Reputation points Independent Advisor
    2026-06-02T15:55:42.76+00:00

    Hi Bruce,

    If Azure Backup is failing only for one Server 2019 VM while others succeed, the first thing to check is the VSS writers on that VM.

    Run vssadmin list writers and confirm that the System Writer and COM+ Writer are stable and not in a failed state.

    If they show errors, restart the COM+ Event System and Volume Shadow Copy services, then retry the backup.

    Verify that the Azure Backup Agent is up to date and that the C:\Windows\System32\wbengine.exe process can run without access issues.

    Corrupted or missing components in the Windows Server Backup feature can cause system state backup failures, so ensure the feature is installed via ServerManagerCmd -install Windows-Server-Backup and check for Event IDs 517 or 12289 in the Application log, which usually point to VSS or provider issues. If all writers are healthy and the agent is current, the issue is likely specific to that VM’s OS state, and you may need to re-register VSS with regsvr32 /i %windir%\system32\eventcls.dll and related DLLs. If the problem persists after these checks, it’s best to open a support case with Microsoft since system state backup failures can stem from deeper OS corruption that requires official remediation.

    Harry.

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  2. AI answer

    2026-06-02T15:24:42.9133333+00:00

    Follow these steps on the failing Windows Server 2019 VM to isolate and fix the System State backup issue with the Microsoft Azure Recovery Services (MARS) agent:

    1. Run the basic MARS/System State checks
      1. Ensure the MARS agent is up to date and the service is running.
      2. Verify network connectivity from the VM to Azure as per MARS troubleshooting.
      3. Confirm at least 5–10% free space on the scratch/cache volume used by MARS.
      4. Make sure antivirus or other backup software is not interfering with Azure Backup; temporarily exclude the MARS folders or pause other backup tools.
      5. Confirm the OS is fully patched and system clock/time zone are correct.
      6. Ensure .NET Framework 4.6.2 or higher is installed.
    2. Verify System State support and prerequisites
      1. System State backup with MARS is supported only for on‑premises Windows Servers, not Azure VMs. If this is an Azure VM, System State via MARS is not supported; use Azure VM backup instead.
      2. On the failing server, check that Windows Server Backup (WSB) is installed:
        • Run in PowerShell: 
                  Get-WindowsFeature Windows-Server-Backup
        • If Install State is “Available”, install it: 
                  Install-WindowsFeature -Name Windows-Server-Backup
      3. Check permissions on C:\System Volume Information and ensure the Local SYSTEM account has Full Control.
      4. Confirm required services are running:
        • Remote Procedure Call (RPC) – Automatic
        • COM+ Event System (EventSystem) – Automatic
        • System Event Notification Service (SENS) – Automatic
        • Volume Shadow Copy (VSS) – Manual (but able to start)
        • Microsoft Software Shadow Copy Provider (SWPRV) – Manual
    3. Validate Windows Server Backup (WSB) itself
      1. From elevated PowerShell, run: 
              Get-WBJob
        • If Get-WBJob is not recognized, reinstall the Windows Server Backup feature.
      2. Run a direct System State backup using WSB (replace X: with a local volume with enough free space): 
              wbadmin start systemstatebackup -backuptarget:X: -quiet
      3. Monitor the job: 
              Get-WBJob
      Get-WBJob -Previous 1
      4. If this WSB job fails, the issue is with WSB/VSS on that VM, and MARS System State backups will also fail until WSB is fixed.
    4. Check for common VSS/System State errors
      1. VSS writer timeout (0x800423f2):
        • In Application event logs, look for VSS errors like “writer’s time-out expired between the Freeze and Thaw events.”
        • Free CPU and memory (stop high‑usage processes) and ensure no other backup is running at the same time; then retry.
      2. Insufficient disk space for shadow copies:
        • In System logs, look for volsnap warnings such as insufficient disk space on C: to grow shadow copy storage.
        • Free space on the indicated volume and, if needed, adjust shadow copy storage using vssadmin resize shadowstorage as described in the referenced article.
      3. EFI partition locked:
        • If MARS reports “EFI system partition is locked,” check for third‑party security or backup software accessing the EFI partition.
        • Configure the security/AV product to allow MARS or wait for other backup jobs to complete before retrying.
    5. If error ID 8007007B appears (invalid path in System State) If the MARS job details or WSB Failure Logs show messages like:
      • “The filename, directory name or volume label syntax is incorrect” (HResult: 80780049, DetailedHResult: 8007007B), or
      • Error in backup of Systemroot_path during enumerate: Error [0x8007007b] ...
      Then follow this registry‑level fix on the failing VM:
      1. Open the WSB Failure Logs from the MARS job and confirm the Systemroot_path is correct (for example it should resemble C:\Windows\\systemroot\).
      2. Run from an elevated command prompt: 
              diskshadow /l C:\outputfilepath.txt
      3. At the DISKSHADOW> prompt, run: 
              list writers detailed
      
      exit
      4. Open C:\outputfilepath.txt and locate the line with Systemroot_path and the associated File_Spec_Path, for example: 
              File List: Path = C:\windows\\systemroot\system32\drivers, Filespec = winmad.sys
      5. Open Registry Editor (regedit) and go to: HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Services
      6. Right‑click Services → Find, and search for the File_Spec_Path found in the output file.
      7. Correct the invalid path entries as indicated in the article so that the file specification used by the System State writer is valid.
      8. Re‑run the WSB System State backup; once it succeeds, retry the MARS System State backup.
    6. Compare with a working VM Since other similar VMs are backing up successfully, compare:
      • Installed roles/features (especially Windows Server Backup).
      • VSS writer status (vssadmin list writers).
      • Disk free space and shadow copy configuration.
      • Presence of any extra security/backup/AV software only on the failing VM.

    After WSB System State backup runs successfully on this Server 2019 VM and VSS errors are resolved, MARS System State backups should also succeed.

    References:

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