The Designer could not be shown for this file because none of the classes within it can be designed.

Trevor Daniels 31

I have a project produced in Visual Studio 2017. I have just downloaded Visual Studio 2022 and tried to open the project. Although all of the code can be viewed, I can't see any of the Forms. I get:

"The Designer could not be shown for this file because none of the classes within it can be designed. The designer inspected the following classes in the file: StartForm - the Base class 'System.Windows.Forms.Form' could not be loaded. Ensure that the assembly has been referenced and that all projects have been built."

Can someone please explain this and offer a solution?

Xingyu Zhao-MSFT 5,381 Reputation points

2021-08-30T02:14:12.947+00:00

Hi @Trevor Daniels ,
Did you design your app with the "Any CPU" option? It will cause your code to JIT to 32-bit on 32-bit platforms and 64-bit on 64-bit platforms.
More details you can refer to Visual Studio designer in x64 doesn't work
Hope it could be helpful.
Xingyu Zhao-MSFT 5,381 Reputation points

2021-09-06T05:26:29.793+00:00

Hi @Trevor Daniels ,
Do you still meet this issue? Please let me know if you need further help.
Trevor Daniels 31 Reputation points

2021-09-06T06:32:12.997+00:00

I do still have the issue. The original project in VS2017 is set to any CPU and this is a 64bit system. In vs 2017 everything works fine.
This morning I opened the project in vs2017, then opened it in vs2022. The project worked great in vs2022, including all the forms. I closed it down and repeated the process and it returned to the original problem with the forms designer; consequently I'm giving up on vs2022 !!!
John Spano 6 Reputation points

2021-11-08T18:26:46.877+00:00

any word on this being fixed? the main 2022 is out this morning and i can't open ANY winform that inherits from any base class. Even ones in the same solution.
says it can't find XYZ base class etc.
Enzo Varenna 1 Reputation point

2021-11-16T15:58:41.55+00:00

Same for me, I have a form class derived from 'System.Windows.Forms.Form' and cannot open any winform in my project.
Stuck in Visual studio 2019, here non problem
Faizan Zareen 1 Reputation point

2022-11-27T08:00:40.43+00:00

Hey dears,

is there any solution for that? am also having same error. designed the forms using VS2019. sometimes it opens the forms in designer but trying from the morning but failed to load it with the same error. what to do?
Jessie Chua Hui May 0 Reputation points

2023-08-09T02:10:29.2333333+00:00

I'm having the same issue.

I tried to open the forms designer in VS2022 but it shows error "Base Class could not be loaded".

There were no issue in VS 2017 or VS2019.

Any solution for this?

6 answers

Julio Nobre 1 Reputation point

2022-09-01T08:00:57.717+00:00

As of today, using Microsoft Visual Studio Professional 2022 (64-bit) - Current - Version 17.3.3, C# Form Designer is unable to design previous forms.

Fortunately, using Microsoft Visual Studio Professional 2019 (32 bit, i guess) - Version 16.9.4, C# Form Designer allows me to proceed my work.
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The Designer could not be shown for this file because none of the classes within it can be designed.

6 answers

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