Hi Hamid badi,
We have checked the reported issue with the provided
details. But we are unable to reproduce the reported issue on our end. By
default, when you close the application and re-open it, the assemblies do not
restore properly. That’s why the designer view does not load properly, and
these assemblies are restored once you rebuild the application. You can
overcome this issue by closing the form window and reopening it once the
application is built and the assemblies are properly referred to. Could you
please check and confirm this? If you are still facing the reported issue,
could you please share which operation (Like adding the particular control)
will cause the designer failure? It will be helpful for us to check on it and
provide you with a solution as soon as possible.
Tested screenshot:

Regards,
Dhanasekar M.