I had to reinstall my Ubuntu and decided to go for Ubuntu 22.04 (at time of writing 2022-02-06it was a prerelease) and the first thing I noted is that grub didn’t allow me any more to have my dual boot with Windows. It simply didn’t show the boot entry.
There is a longer explanation about the OS Prober in Grub 2.06+ under
which is a security feature. So it’s on you to make the call if you like to re-enable the OS Prober to allow for dual boot.
There is also a nice read up under
If that’s too long to read, tl;dr here is the quick fix to enable the OS Prober in Ubuntu grub.
Step 1: edit /etc/default/grub to add GRUB_DISABLE_OS_PROBER=false maybe under GRUB_CMDLINE_LINUX
sudo vi /etc/default/grub GRUB_CMDLINE_LINUX="" GRUB_DISABLE_OS_PROBER=false
Step 2: update grub to apply the new settings and then reboot the system
sudo update-grub reboot
And now you should have your old grub back with Windows and other OSes if you had.
Again, please keep in mind this was a security update, so please understand the implications.