Developer technologies | Windows Forms
A set of .NET Framework managed libraries for developing graphical user interfaces.
![](data:image/svg+xml, %3Csvg xmlns='http://www.w3.org/2000/svg' height='64' class='font-weight-bold' style='font: 600 30.11764705882353px "SegoeUI", Arial' width='64'%3E%3Ccircle fill='hsl(198.4, 38%, 29%)' cx='32' cy='32' r='32' /%3E%3Ctext x='50%25' y='55%25' dominant-baseline='middle' text-anchor='middle' fill='%23FFF' %3EOM%3C/text%3E%3C/svg%3E)
For me it helped to execute Application.DoEvents() a few times.
Windows Forms Application Icon suddenly shows as default icon or does not update color after KB5051989 update
![](data:image/svg+xml, %3Csvg xmlns='http://www.w3.org/2000/svg' height='64' class='font-weight-bold' style='font: 600 30.11764705882353px "SegoeUI", Arial' width='64'%3E%3Ccircle fill='hsl(41.6, 12%, 14%)' cx='32' cy='32' r='32' /%3E%3Ctext x='50%25' y='55%25' dominant-baseline='middle' text-anchor='middle' fill='%23FFF' %3EEG%3C/text%3E%3C/svg%3E)
Emmanuel Guballa
25
Reputation points
Hi,
Our C# Windows Forms Application icon (in the taskbar) suddenly shows as default icon or sometimes doesn't update its color (based on the customization) after installing the KB5051989 update. This has been working for 15 years, and the issue just appeared after the said update. Removing the update will make it work as usual. We have a VM that only have the KB5051979 update and there, the problem doesn't show up. The issue was also experienced by our clients, and we can also see this internally. Even after clearing the icon cache and rebuilding it, the problem still occurs.
There were a few cases, wherein I locked my machine while the application is running. And when I came back and logged in after a few minutes, the icon is displayed properly and with the correct color customization.
Here is a sample screenshot of the issue.
And here is the working one, without the update.
Here is the case where the taskbar icon did not update the color in the taskbar, but it is correctly shown in the Task Manager and in the live preview:
Is there something with K8SOS1989 update that may have affected taskbar icons of windows forms applications?
Any other advice that we can try to make it work as before?
Regards,
Emman G
Developer technologies | Windows Forms
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![](data:image/svg+xml, %3Csvg xmlns='http://www.w3.org/2000/svg' height='64' class='font-weight-bold' style='font: 600 30.11764705882353px "SegoeUI", Arial' width='64'%3E%3Ccircle fill='hsl(128, 8%, 22%)' cx='32' cy='32' r='32' /%3E%3Ctext x='50%25' y='55%25' dominant-baseline='middle' text-anchor='middle' fill='%23FFF' %3EA%3C/text%3E%3C/svg%3E)
Anonymous2025-03-06T09:48:16.9866667+00:00 Hi @Emmanuel Guballa ,Welcome to Microsoft Q&A,
We haven't reproduced this issue yet. What version of the system are you using?Can you provide steps to reproduce the problem? After installing the patch, will the same problem occur when creating a new program? Maybe it is due to compatibility issues with some third-party plug-ins.
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Emmanuel Guballa 25 Reputation points
2025-03-06T10:33:33.96+00:00 Hi @Anonymous
Thanks for your reply. I am currently using Windows 11 Enterprise 23H2. Right now, I am in the process of creating a small project which will try to reproduce the said problem.
But for some context, we initially show an icon set in the project properties during login. Once the main application window appears, the icon gets updated from having a circle background to a square background (this works sometimes now). And then, upon entering the application, the square icon background will change its color based on the customization. Basically, we are using two images for the square background icon (1: a image, 2: square image). We change the color of both, depending on the customization and put them in a single image using Graphics class. This will then be set to the Icon property.
What patch are you referring to? I will have to ask our IT department to have that patch so we can check.
It has been working for the last 15 years and suddenly this happened. Not only internally but also to some of our clients who upgraded.
We are trying to create a support ticket as well so this can be checked further.
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Anonymous
2025-03-07T03:03:37.83+00:00 Hi @Emmanuel Guballa , Welcome to Microsoft Q&A,
The project we created is currently unable to reproduce your problem. If you can't create a stable reproduction of the problem, it will be difficult to solve your problem. The patch I'm talking about is KB5051989, and there is currently an updated preview version KB5052094. We are currently unable to determine whether the problem is due to some specific system environment. I'm sorry that the program you have been using normally for a long time suddenly has problems.
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![](data:image/svg+xml, %3Csvg xmlns='http://www.w3.org/2000/svg' height='64' class='font-weight-bold' style='font: 600 30.11764705882353px "SegoeUI", Arial' width='64'%3E%3Ccircle fill='hsl(313.6, 72%, 40%)' cx='32' cy='32' r='32' /%3E%3Ctext x='50%25' y='55%25' dominant-baseline='middle' text-anchor='middle' fill='%23FFF' %3EEK%3C/text%3E%3C/svg%3E)
Eduard Kobzik 0 Reputation points2025-03-09T21:16:11.1866667+00:00 Hi @Emmanuel Guballa @Anonymous
I'm able to reproduce the issue as well
System description: Win11 23H2-24H2
App description - WPF application on .NET 4.8
Issue is not reproducible when KB5051989 reverted
Issue is not reproducible when app started under Administrator
Issue disappears in case Windows Explorer restarted from Task Manager (but after app restart, icon disapper)
Clearing Icon Cache does not help -
Anonymous
2025-03-10T01:53:33.4833333+00:00 I'll confirm again, you seem to be talking about a WPF project, but your question is about a WinForms project. What project are you having the problem on?
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Anonymous
2025-03-12T02:56:44.3933333+00:00 We are sorry that we cannot solve your problem immediately. Regarding your problem, it is more affected by the KB5051989 patch, which is more related to the Windows team. For WinForms and WPF tags, we are more aware of and handle code-related issues.
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![](data:image/svg+xml, %3Csvg xmlns='http://www.w3.org/2000/svg' height='64' class='font-weight-bold' style='font: 600 30.11764705882353px "SegoeUI", Arial' width='64'%3E%3Ccircle fill='hsl(278.4, 73%, 36%)' cx='32' cy='32' r='32' /%3E%3Ctext x='50%25' y='55%25' dominant-baseline='middle' text-anchor='middle' fill='%23FFF' %3EAN%3C/text%3E%3C/svg%3E)
António Fernandes 0 Reputation points2025-03-27T17:56:19.7966667+00:00 Is there any more information about this.
We're having the same problem, and sometimes it just goes away by itsef...
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![](data:image/svg+xml, %3Csvg xmlns='http://www.w3.org/2000/svg' height='64' class='font-weight-bold' style='font: 600 30.11764705882353px "SegoeUI", Arial' width='64'%3E%3Ccircle fill='hsl(265.6, 61%, 35%)' cx='32' cy='32' r='32' /%3E%3Ctext x='50%25' y='55%25' dominant-baseline='middle' text-anchor='middle' fill='%23FFF' %3EMS%3C/text%3E%3C/svg%3E)
Martin Suchan 5 Reputation points2025-03-30T09:31:14.2166667+00:00 We're seeing the same problem with our WPF project using .NET Framework 4.8 on Windows 11 22H2, and also on WinForms .NET 8.0 app on Windows 11 24H2.
This is clearly a Windows 11 regression that needs to be fixed.
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![](data:image/svg+xml, %3Csvg xmlns='http://www.w3.org/2000/svg' height='64' class='font-weight-bold' style='font: 600 30.11764705882353px "SegoeUI", Arial' width='64'%3E%3Ccircle fill='hsl(64, 36%, 16%)' cx='32' cy='32' r='32' /%3E%3Ctext x='50%25' y='55%25' dominant-baseline='middle' text-anchor='middle' fill='%23FFF' %3EEZ%3C/text%3E%3C/svg%3E)
Edward Ziemiński 0 Reputation points2025-03-31T16:54:15.6633333+00:00 I and my teammates observe the same problem in two separate WPF projects. One is built on top of .NET 8, and the other one uses .NET 9. Our users also raise the same issue.
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![](data:image/svg+xml, %3Csvg xmlns='http://www.w3.org/2000/svg' height='64' class='font-weight-bold' style='font: 600 30.11764705882353px "SegoeUI", Arial' width='64'%3E%3Ccircle fill='hsl(208, 16%, 30%)' cx='32' cy='32' r='32' /%3E%3Ctext x='50%25' y='55%25' dominant-baseline='middle' text-anchor='middle' fill='%23FFF' %3EMC%3C/text%3E%3C/svg%3E)
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![](data:image/svg+xml, %3Csvg xmlns='http://www.w3.org/2000/svg' height='64' class='font-weight-bold' style='font: 600 30.11764705882353px "SegoeUI", Arial' width='64'%3E%3Ccircle fill='hsl(259.20000000000005, 57.00000000000001%, 35%)' cx='32' cy='32' r='32' /%3E%3Ctext x='50%25' y='55%25' dominant-baseline='middle' text-anchor='middle' fill='%23FFF' %3EGG%3C/text%3E%3C/svg%3E)
Gschwandegger Gerald 5 Reputation points2025-05-06T05:06:44.6133333+00:00 i have the same issue. i tried a lot of different things. If I start the program and pin it to the taskbar, the icon is displayed. As soon as I unpin it from the taskbar, the icon disappears again.
The following steps also failed:
- Generating a new icon and storing it in the program
- Clearing the icon cache
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![](data:image/svg+xml, %3Csvg xmlns='http://www.w3.org/2000/svg' height='64' class='font-weight-bold' style='font: 600 30.11764705882353px "SegoeUI", Arial' width='64'%3E%3Ccircle fill='hsl(115.19999999999999, 23%, 21%)' cx='32' cy='32' r='32' /%3E%3Ctext x='50%25' y='55%25' dominant-baseline='middle' text-anchor='middle' fill='%23FFF' %3EAA%3C/text%3E%3C/svg%3E)
ANIKIN Alexey 0 Reputation points2025-05-22T13:26:37.3366667+00:00 I have the same issue since resent time.
Windows 11 Enterprise23H2
22631.5039
WPF application on .NET 4.8
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![](data:image/svg+xml, %3Csvg xmlns='http://www.w3.org/2000/svg' height='64' class='font-weight-bold' style='font: 600 30.11764705882353px "SegoeUI", Arial' width='64'%3E%3Ccircle fill='hsl(19.2, 56.00000000000001%, 11%)' cx='32' cy='32' r='32' /%3E%3Ctext x='50%25' y='55%25' dominant-baseline='middle' text-anchor='middle' fill='%23FFF' %3EA%3C/text%3E%3C/svg%3E)
afuentes 5 Reputation points2025-05-22T18:37:03.7733333+00:00 I am experiencing the same issue on Windows 11 Enterprise 23H2 (22631). Windows Form application on .NET Framework 4.8. If I start the program and pin it to the taskbar, the icon is displayed. As soon as I unpin it from the taskbar, the icon disappears again.
Following code seems to work, but I am not convinced of this solution. I still can see the default icon until it is updated during the load of the form, so the icon is not adequately rendered by File Explorer. If I restart File Explorer, the icon is shown perfectly. Weird...
private void Form1_Load(object sender, EventArgs e)
{
this.Icon = new Icon("xxx.ico");}
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![](data:image/svg+xml, %3Csvg xmlns='http://www.w3.org/2000/svg' height='64' class='font-weight-bold' style='font: 600 30.11764705882353px "SegoeUI", Arial' width='64'%3E%3Ccircle fill='hsl(32, 56.00000000000001%, 13%)' cx='32' cy='32' r='32' /%3E%3Ctext x='50%25' y='55%25' dominant-baseline='middle' text-anchor='middle' fill='%23FFF' %3ESV%3C/text%3E%3C/svg%3E)
Stijn Vanpraet 0 Reputation points2025-08-03T17:01:14.53+00:00 Same issue here (win11, VS 2022, .net 9.0, avalonia mvvm desktop app).
This does not happen when built with 'Debug' configuration, only with 'Release' or any other custom configuration added to the project.Restarting Explorer.exe after starting the app fixes it as mentioned above.
@afuentes workaround implemented for now...
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![](data:image/svg+xml, %3Csvg xmlns='http://www.w3.org/2000/svg' height='64' class='font-weight-bold' style='font: 600 30.11764705882353px "SegoeUI", Arial' width='64'%3E%3Ccircle fill='hsl(297.6, 2%, 38%)' cx='32' cy='32' r='32' /%3E%3Ctext x='50%25' y='55%25' dominant-baseline='middle' text-anchor='middle' fill='%23FFF' %3EL%3C/text%3E%3C/svg%3E)
LukasD 0 Reputation points2025-10-20T09:44:21.9833333+00:00 I have the issue with the icon but KB5051989 is not installed. No reproduction steps known, it just happens.
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