Feb 2026 Cumulative Update (KB5075904) for Windows Server 2019 Broke Cygwin, Cannot Uninstall Successfully

Question

We have a machine running Windows Server 2019 which updated automatically to KB5075904 on 2/10. After that update certain Cygwin features installed on the machine ceased to function correctly -- most notably Git for Cygwin.

Realizing the issue, we attempted to uninstall the update via the GUI, and it did not work. We then used dism to uninstall the update. The uninstall process flatlined at 70.4% for several hours, at which point we rebooted the server. The winver now shows the correct previous image, and that KB5075904 is no longer installed but dism scanhealth shows the image is in a repairable state.

The repair via dism also stalls but at 100% without ever completing.

Additionally, Git for Cygwin is still broken.

There were known problems with the January cumulative update on some systems,; we did not experience those. Are there known problems with KB5075904?

What should our next steps be to get back to a healthy state, with Cygwin running all packages correctly?

Answer 1

Hello G Boz, I’m Henry, and I’d like to share my thoughts on your issue.

From my research, the KB update itself does not appear to have widespread problems. Based on your description, the sequence seems to be: KB installed → Git stopped working → KB uninstalled → Git still broken. This suggests the underlying Windows Server image may have become unhealthy. A quick option is to re‑run the Cygwin setup, which forces Windows to check all installed packages for corruption and repair inconsistencies without affecting your data or settings. However, this only addresses the Cygwin symptoms.

If the Cygwin repair does not work, or if you experience any other issues, I strongly recommend repairing the Windows image itself using the dism command with an installation source as the next step. Please ensure you have a recent backup before starting.

1. Download the Windows Server ISO from Microsoft: Windows Server 2019 Evaluation Center
2. Mount the ISO
   • Right‑click the ISO and select Mount. Note the drive letter (e.g., X:).
   • Open Command Prompt as Administrator and run dism /get-wiminfom /wimfile:X:\sources\install.wim
3. Run DISM with a Source dism /online /cleanup-image /restorehealth /source:WIM:X:\sources\install.wim:1 /limitaccess Replace X: with your ISO drive letter and :1 with the correct index. This forces DISM to use local files instead of Windows Update.
4. Run System File Checker (SFC): sfc /scannow After completion, reboot the server. With the OS image repaired, the Cygwin issue may resolve automatically.

I hope you’ll try these steps and let me know how it goes. If this answer helps, feel free to click Accept Answer so others can benefit too.

Answer 2

It seems you are experiencing issues with the Windows Server 2019 cumulative update KB5075904 affecting Cygwin functionality, particularly with Git. While there are no specific references in the provided context regarding known problems with KB5075904, the general approach to resolving Windows Update issues involves using the DISM tool and the SFC command to repair any potential corruption in the system image.

Since you mentioned that the DISM repair process stalls at 100%, you might want to consider the following steps:

1. Run SFC Command: After attempting DISM, run the System File Checker to check for and repair corrupted system files. Open an elevated command prompt and execute:

      sfc /scannow
   

   This may help in identifying and fixing any issues that are affecting Cygwin.
2. Check CBS.log: Review the CBS.log file located at %windir%\Logs\CBS\CBS.log for any specific errors that might indicate what went wrong during the DISM or SFC processes.
3. Reinstall Cygwin: If Cygwin is still broken after performing the above steps, consider uninstalling and then reinstalling Cygwin. This can help reset any configurations that might have been affected by the update.
4. Manual Repair: If issues persist, you might need to manually repair corrupted files by extracting the necessary files from a known good source and using the DISM command with the /Source option as mentioned in the context.
5. Check for Further Updates: Keep an eye on any subsequent updates from Microsoft that may address issues related to KB5075904 or other cumulative updates.

If the problem continues, you may want to reach out to Microsoft support for more tailored assistance regarding the specific update and its impact on your system.

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References:

• Fix Windows Update corruptions and installation failures
• Advanced guide to fix CBS corruption manually using DISM utility