on a pc where I had both Windows 7 and Fedora 29, with boot loader configured in linux and grub2, I have run the update to Fedora 30 using the usual procedure described here, and already completed on another pc (but without the dual boot...):

after the commad 
sudo dnf system-upgrade reboot
I saw the laptop rebooting, installing all the about 9k packages, than verifying them and as soon as it had verified the last one, I saw again reboot (is it expected?), but then in grub options I only see

windows 7
windows 7 recovery environment

So I think something went bad in updating grub2 config...
Any hint on how to recover grub, eventually booting from a usb stick in any way?

Already happened to anyone else with f29 to f30?
I followed on the same laptop the same procedure without problems from f26 (or f27) to f29 until this problem.