I found an answer here saying to use gparted, but it does not function for me. Gparted lists the partition in the list but does not show it in the top bar (I see nothing between /dev/sda3 and /dev/sda5).
Gparted says File system : extended ; Status : Busy (At least one logical partition is mounted) Path : /dev/sda4
But Gparted does not give me the mount point.
I think this partition was created by an ancient attempt at installing kubuntu. On /dev/sda5 I have a functioning Kubuntu. On the first 3 there is windows.
I'm running out of space on /dev/sda5. Its 122.49 GiB. /dev/sda4 is also 122.49 GiB.
sudo mount /dev/sda4 /media/kube/STORAGE mount: /media/kube/STORAGE: /dev/sda4 is not a valid block device.
I cannot try umount because I don't know the mount point.