Dualboot upgrading needs extra care
Upgrading dual boot machines goes fine, but Grub does not automatically recognize that the computer also holds Windows.
This feature was introduced in Grub 2.06.
After upgrading and resetting, input this command as administrator to make Windows noticed again:
echo "GRUB_DISABLE_OS_PROBER=false >> /etc/default/grub && update-grub
This probably should be made as an default option for dual-booted hosts.
This is not a full fix though, since Windows should be default on dual boot machines. Edit /etc/default/grub
with GRUB_DEFAULT=2
to achieve this (see manual).
Edited by Mikko Halmela