After waiting for some time,booting fails saying some disks cannot be found, and I need to regenerate initramfs. I have no idea what has happened,or how to recover from this problem. Please can anyone help me?

Boot to previous kernel is usually where I start. Then may have to remove or re-install updates.

In some cases you have to fully power down system. Usb media acts funny sometimes on reboots.

Could be an issue with uefi.

It's possible that the update didn't correctly work on the boot loader or maybe boot loader was seen at two places.

My Dell laptop Inspiron boots up via UEFI, and the booting off the USB worked OK when next I booted off it for some reason best known to itself. It seems it may even be something to do with which USB 3.0 port I plug the USB disk into. I'm now getting some success booting off my Verbatim 500 Gb USB 3.0 external disk, though I haven't yet worked out which combination of actions while booting up works 100% of the time. I think GRUB is somehow or other (whether it's resident on the Laptop Windows hard drive (C:\) or on the USB External disk where Fedora 32 is installed and running (sometimes) from).
Any ideas how I can track down & fix where things are going wrong? I really appreciate any help I can get with this.
Thanks.