Status & solution for Windows 11 update (KB5066835) and GMG ColorServer 5

Problem report: Microsoft Windows 11 update interrupts ColorServer 5 data processing

In this article you can find all current information, workarounds and solutions about this issue. If you have any further questions or problems, please contact customercare@gmgcolor.com with the keyword ‘Windows 11 KB5066835’. We will update this article with new information as soon as it is available.

Status as of 19 October 2025

Microsoft has solved this issue. Please reactivate the Windows updates again and make sure that all subsequent Microsoft patches are installed, to ensure that GMG ColorServer can run smoothly.

Status as of 18 October 2025

Microsoft confirms the issue and is working on releasing a resolution in a future Windows update. More information: Windows 11, version 25H2 known issues and notifications

Status as of 16 October 2025

Description of the problem

The Microsoft Windows 11 update from 15 October 2025 (KB5066835, version 24H2) causes a problem with GMG ColorServer 5 (all versions!): The application starts, but can no longer process jobs. For users, it appears as if the server is unavailable. (The problem is caused by changes in HTTP/2 communication affected by the Windows update.)

A ColorServer system notification states that data is being processed - but this is actually not happening. 


In the Windows update history, you can see whether the update was installed or not.

Workaround

Please uninstall the Windows update KB5066835 from 15 October 2025 if it has already been installed and temporarily pause automatic updates until a solution is available. Please contact your IT administration if GMG ColorServer is running in an IT-managed environment.

1. Here you will find instructions for uninstalling the update.
2. Here you will find instructions for temporarily pausing updates.