I have this problem, please help me! I don't want to reinstall ubuntu as I've done several times
nico@home:~$ sudo umount /dev/sda3
umount: /: target is busy.
nico@home:~$ fsck
fsck from util-linux 2.37.2
e2fsck 1.46.5 (30-Dec-2021)
/dev/sda3 is mounted.
WARNING!!! The filesystem is mounted. If you continue you *WILL*
cause *SEVERE* filesystem damage.
Do you really want to continue<n>? no
check aborted.
fsck.fat 4.2 (2021-01-31)
open: Permission denied
