Fix KB5044284 Windows Server 2025 Veeam Indexing Error

Veeam backup jobs are failing because guest indexing incorrectly identifies a Windows Server 2025 VM as a Linux machine. This is caused by the update KB5044284.

The Fix

Follow these methods in order. Start with the immediate workaround to restore backups, then apply the preventative measure.

Method 1: Disable Veeam Guest Indexing (Immediate Workaround)

This bypasses the failing component. In the Veeam Backup & Replication console, edit the affected backup job. Navigate to the Guest Processing tab and uncheck "Enable application-aware processing." Save the job and rerun it. Backups will complete without guest file indexing.

If That Doesn't Work:

Apply the setting via PowerShell on your Veeam server:

Connect-VBRServer
$job = Get-VBRJob -Name "Your_Backup_Job_Name"
$job | Set-VBRJobOptions -DisableGuestProcessing

Method 2: Block and Remove KB5044284 (Prevent Recurrence)

The root cause is KB5044284. On affected servers (now showing Windows Server 2025 in winver), first uninstall the update if possible:

$KB = "KB5044284"
Get-Hotfix | Where-Object {$_.HotfixID -like "$KB"} | Uninstall-Hotfix -Force

Immediately block it from reinstalling. Use Group Policy to manage update classifications or, on individual servers, use the registry:

New-ItemProperty -Path "HKLM:\SOFTWARE\Policies\Microsoft\Windows\WindowsUpdate" -Name "ExcludeWUDriversInQualityUpdate" -Value 1 -PropertyType DWord -Force

Also configure your third-party patch management tool (Ivanti, Heimdal, BMC, etc.) to exclude this KB.

If That Doesn't Work:

If the server is now an unlicensed Windows Server 2025 and is unstable, you must revert. Boot the VM from a Windows Server 2022 ISO, select "Repair your computer," then "Troubleshoot," and "Uninstall Updates" to remove KB5044284. A restore from a pre-upgrade backup or snapshot is the alternative.

Method 3: Long-Term Resolution

Upgrade Veeam Backup & Replication to version 12.3 or later, which includes official support for Windows Server 2025 guest indexing. This is the permanent fix once your environment is ready for the new OS.

Verify

Confirm the issue is resolved by checking these points:

1. Backup Job Status: The failing Veeam job now completes successfully. Check the job history for a "Success" status.

2. Update Status: Run Get-Hotfix -Id KB5044284 in PowerShell. An error stating the update is not installed confirms removal.

3. OS Version: Run winver on the affected server. It should no longer report "Windows Server 2025" if you successfully reverted. If it does, you are relying on Method 1 (indexing disabled) until Veeam is upgraded.

4. Patch Management: Verify your RMM or patch management console shows KB5044284 as permanently hidden or declined.

The most common mistake is treating this as only a Veeam error. Always confirm the guest OS version first. Disabling application-aware processing is the fastest workaround, but blocking KB5044284 is necessary to prevent this issue from impacting other servers.