This is not CubeMX error with export. You don't have DFP drivers for Keil to be able to work with STM32F0 family. On the window behind your message (referring to image), findSTMicroelectronics on left side and then on right one, install STM32F0 package.
If you use Alt+Print-Screen, it will just capture the current dialogue - rather than your entire screen.
Attaching the screenshot is not so helpful - as we can't see it in context.
Just paste it into the post - where we can see it:
Did you not just try pressing the 'Install' button ?
A complex system that works is invariably found to have evolved from a simple system that worked.A complex system designed from scratch never works and cannot be patched up to make it work.
, DFP drivers are installed but every time I edit a project on cube mx I have to redo the procedure of selecting the micro asyou advises (not automatically). I have uninstalled and reinstalled both keil and cube and I have not solved the problem. I have performed a new installation of both in another pc and I always have the same error.