Windows Server 2025 Standard error - 0x800f0991

[mrkhachaturov]

Hello everyone,

I recently discovered this amazing community, and after browsing several threads, I was impressed by how dedicated everyone is to helping each other. That’s why I decided to make a donation to support the great work being done here.

I’m currently running a lab setup with Windows Server 2025 and have encountered an issue while trying to update. Thanks to advice found in previous threads, I was able to resolve a hash mismatch error and restore the necessary files.

However, I’m now facing a different problem. I’m receiving error 0x800f0991 on my Windows Server 2025 Standard, which is also acting as an Active Directory server. When I try to add new roles, I get a notification that some components are corrupted.
I have tried all this command.

1. SFC /Scannow
2. DISM /Online /Cleanup-Image /CheckHealth
3. DISM /Online /Cleanup-Image /ScanHealth
4. DISM /Online /Cleanup-Image /restoreHealth
5. DISM /Online /Cleanup-Image /RestoreHealth /Source:\\IVN-DC02\WinSxS /LimitAccess ( Source was defined to second Active Directory Server running Windows Server 2025)
6. dism /online /cleanup-image /startcomponentcleanup

---

Result of commandSFC /Scannow

Beginning system scan.  This process will take some time.

Beginning verification phase of system scan.
Verification 100% complete.

Windows Resource Protection did not find any integrity violations.

Result of commandDISM /Online /Cleanup-Image /restoreHealth

Deployment Image Servicing and Management tool
Version: 10.0.26100.1150

Image Version: 10.0.26100.2894

[==========================100.0%==========================]
Error: 0x800f081f

The source files could not be found.
Use the "Source" option to specify the location of the files that are required to restore the feature. For more information on specifying a source location, see https://go.microsoft.com/fwlink/?LinkId=243077.

The DISM log file can be found at C:\WINDOWS\Logs\DISM\dism.log

CBS logs folder was too large for attachment, so here is the link to download from www.wetransfer.com, the link is valid only for 3 days, mirror link to download from my google drive.

ComponentsScanner, DISM, SFCFix log files and COMPONENTS file from C:\WINDOWS\System32\config you can find in attachment.

 

[Windows Update Bot]

Hi @mrkhachaturov,

Welcome to Sysnative Forums!

If you haven't already, please review the posting instructions here, and attach the requested log files. Without log files, our helpers will not be able to assist, and this will slow down fixing your machine.

If logs have been already been provided, our team of volunteers will analyse the provided log files to build a fix for your system. Please be aware that this may take several days from your initial post, due to the high volume of threads that we receive.


- Sysnative Windows Update Team

 

[mrkhachaturov]

Build version is 26100.2894.
Downloaded ISO from https://uupdump.net selecting only Windows 2025 Server Standart.
Mounted ISO and runned Repair-WindowsImage -Online -RestoreHealth -Source "D:\sources\install.wim:1" -LimitAccess
Restore was succefull.

Trying to update system again and getting Install error - 0x800f0991.

Next tried to run dism /online /cleanup-image /startcomponentcleanup

Deployment Image Servicing and Management tool
Version: 10.0.26100.1150

Image Version: 10.0.26100.2894

[==========================100.0%==========================]
The operation completed successfully.

After rebooted and runned SFC /scannow

Beginning system scan.  This process will take some time.

Beginning verification phase of system scan.
Verification 100% complete.

Windows Resource Protection did not find any integrity violations.