A set of .NET Framework managed libraries for developing graphical user interfaces.
Hello @Raneem kamel ,
Thanks for your question.
Base on Windows Forms Designer error page, this error means the control exists in your project's .Designer.cs file, but the Designer cannot load/instantiate it - usually because the assembly hasn't been compiled yet or has a build error.
You can refer to the following steps:
- The designer needs a compiled assembly to find the type. If ctrPersonInformation is in the same project, I suggest building before the Designer can use it.
- Build → Rebuild Solution (Ctrl+Shift+B).
- Then try opening the designer again.
- Clean + Delete bin/obj folders
- Build → Clean Solution
- Manually delete the bin\ and obj\ folders from your project directory.
- Rebuild Solution
- Reopen the Designer
- Verify the namespace & class name match exactly
- Check the error list window for errors inside
ctrPersonInformation.csor its related files. Please fix all errors → rebuild → reopen Designer. - After rebuilding, please close Visual Studio completely. Then, reopen the solution and build before opening any designer.
Please try and let me know if it works. I'd be happy to investigate further.
I hope this addresses your question. If this response was helpful, please consider following the guidance to provide feedback.