WPF window render freezing on windows 11 update 25H2

Question

WPF window render freezing on windows 11 update 25H2

ML 0

Hello.

Our client is reporting worrying problems that started happening after updating windows 11 to version 25H2 (it is possible it was also happening with 24H2, not sure at this moment), but it is definetly not happening in 22H2. Everything else is the same.

The problem is that the rendering for windows application written in WPF XAML simply freezes in one of the core DLL functions. Unfortunately it's hard to replicate it since it does not happen on our end.

It seems to be happening in SyncFlush function of Windows Media Composition somewhere in WPF.

It looks like a function that is responsible for drawing the window, and there is little we can do to affect it. We tried turning hardware acceleration to off but it did not help.

Has anyone seens something similar?

ML 0 Reputation points

2025-12-22T11:17:49.21+00:00

Since the AI responded, I'll add the following:

The issues occurs on multiple devices at clients office, but not on any of ours.

We were trying to pinpoint the common settings for the ones at the client's office but so far, no luck. They seem to be from different vendors (Dell, Lenovo), different GPU (amd, integrated intell) etc.

Hardware drivers therefore are not very likely to affect this either.
ML 0 Reputation points

2025-12-22T11:23:35.1266667+00:00

And one more comment, the AI provided a linke (I found it before myself though), but it's good to use it as a base: https://learn.microsoft.com/en-us/answers/questions/5676215/wpf-window-render-freezing-on-windows-11-update-25?comment=question&translated=false#newest-question-comment

this seems to be the result. However, there is nothing I can do to fix this from what I've tried, and it seems to be tied to the windows update, as in 22H2 it does not happen and in 24H2 and 25H2 it does.
Viorel 125.8K Reputation points

2025-12-22T11:23:42.9233333+00:00

What kind of controls or specific techniques are used?
ML 0 Reputation points

2025-12-22T11:26:29.95+00:00

We're using Telerik's controls, but I doubt its the cause. Otherwise its a standard WPF / XAML application.
Viorel 125.8K Reputation points

2025-12-22T11:31:53.3933333+00:00

Are regular or derived (third-party) controls also used: RichTextBox and TreeView?
ML 0 Reputation points

2025-12-22T11:47:50.28+00:00

We're using RadTreeView which seems to be a form of TreeView, yes. We're also using RichTextBox. Yes. Can this affect it?
ML 0 Reputation points

2025-12-22T12:00:36.02+00:00

RichTextBox is a System.Windows.Controls.RichTextBox control though, so it does not seem like a third party control. We are using telerik's controls though, but even with that, the controls work perfectly fine in 22 version of Windows 11.
Viorel 125.8K Reputation points

2025-12-22T12:30:09.6666667+00:00
By the way, some errors and hangs in SyncFlush are mentioned here:

https://learn.microsoft.com/en-us/troubleshoot/developer/dotnet/framework/general/wpf-render-thread-failures

1 answer

Your answer

ML 0 Reputation points

2025-12-22T11:17:49.21+00:00

Since the AI responded, I'll add the following:

The issues occurs on multiple devices at clients office, but not on any of ours.

We were trying to pinpoint the common settings for the ones at the client's office but so far, no luck. They seem to be from different vendors (Dell, Lenovo), different GPU (amd, integrated intell) etc.

Hardware drivers therefore are not very likely to affect this either.
ML 0 Reputation points

2025-12-22T11:23:35.1266667+00:00

And one more comment, the AI provided a linke (I found it before myself though), but it's good to use it as a base: https://learn.microsoft.com/en-us/answers/questions/5676215/wpf-window-render-freezing-on-windows-11-update-25?comment=question&translated=false#newest-question-comment

this seems to be the result. However, there is nothing I can do to fix this from what I've tried, and it seems to be tied to the windows update, as in 22H2 it does not happen and in 24H2 and 25H2 it does.
Viorel 125.8K Reputation points

2025-12-22T11:23:42.9233333+00:00

What kind of controls or specific techniques are used?
ML 0 Reputation points

2025-12-22T11:26:29.95+00:00

We're using Telerik's controls, but I doubt its the cause. Otherwise its a standard WPF / XAML application.
Viorel 125.8K Reputation points

2025-12-22T11:31:53.3933333+00:00

Are regular or derived (third-party) controls also used: RichTextBox and TreeView?
ML 0 Reputation points

2025-12-22T11:47:50.28+00:00

We're using RadTreeView which seems to be a form of TreeView, yes. We're also using RichTextBox. Yes. Can this affect it?
ML 0 Reputation points

2025-12-22T12:00:36.02+00:00

RichTextBox is a System.Windows.Controls.RichTextBox control though, so it does not seem like a third party control. We are using telerik's controls though, but even with that, the controls work perfectly fine in 22 version of Windows 11.
Viorel 125.8K Reputation points

2025-12-22T12:30:09.6666667+00:00

By the way, some errors and hangs in SyncFlush are mentioned here:

https://learn.microsoft.com/en-us/troubleshoot/developer/dotnet/framework/general/wpf-render-thread-failures

Answer 1

It appears that the freezing issue you are experiencing with WPF applications after updating to Windows 11 version 25H2 may be related to render thread failures, particularly in the SyncFlush function of the Windows Media Composition. Such issues can arise from various causes, including problems with video hardware or drivers, as well as potential bugs in WPF itself when interacting with the graphics hardware.

Since you have already tried disabling hardware acceleration without success, here are some additional recommendations that may help diagnose or mitigate the problem:

Update Video Drivers: Ensure that the video drivers on the affected machines are up to date, as outdated or incompatible drivers can lead to rendering issues.
Monitor Resource Usage: Use Performance Monitor to track memory usage and other resource metrics to identify if the application is exhausting any resources, which could lead to System.OutOfMemoryException errors.
Test on Different Hardware: If possible, test the application on different hardware configurations to see if the issue persists, which could help isolate whether it's a hardware-specific problem.
Check for Known Issues: Review the release notes for Windows updates to see if there are any known issues related to WPF or rendering that have been documented.
Collect Detailed Information: If the issue is reproducible, gather detailed information such as call stacks, crash dumps, and a description of the environment to assist in diagnosing the problem further.

Since the issue does not occur on version 22H2, it may be worth reporting this to Microsoft if it continues to be a problem, as it could indicate a regression or compatibility issue introduced in the newer versions.

References:

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WPF window render freezing on windows 11 update 25H2

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