sao tôi lại bị như này

Hi,

The “Timed out while connecting to named pipe” error means Visual Studio couldn’t connect to the Windows Forms designer process (DesignToolsServer.exe) in time. For WinForms projects targeting .NET (not .NET Framework), the designer runs in a separate process. This error appears when Visual Studio waits for that process longer than the allowed timeout.

Please try this first:

1. Close Visual Studio completely.
2. In the WinFormsApp2 project folder, delete the bin and obj folders.
3. Reopen the solution and select Build > Rebuild Solution.
4. Open Form1.cs [Design] again.

If the error persists, increase the designer timeout. Go to Tools > Options > All Settings > Windows Forms Designer > General, or Tools > Options > Windows Forms Designer > General in Visual Studio 2022. Find Connection timeout (sec), increase the value (for example, to 300), and reopen the designer.

If it still doesn’t work, please click Show Call Stack on the error page and paste the content here. Please also share your Visual Studio version (Help > About) and the .NET version your project targets. That will help identify the root cause.

References:

• Windows Forms Designer error page
• Configure Windows Forms Designer options in Visual Studio

If this resolves your issue, please consider accepting the answer. If the problem persists, let me know and I’ll be happy to keep helping.