Login loop, bash: cannot create temp file for here-document: No space left on device

Question

I'm trying to login to my elementaryOS and i stuck in a loop(i enter password, press enter and it back to login). I entered the terminal (ctrl+alt+f3) to see what's going on with permissions, and i got the error: bash: cannot create temp file for here-document: No space left on device so i checked my partition, and found got this:

Filesystem     Size  Used  Avail Use% Mounted on 
udev           3.9G     0   3.9G   0% /dev
tmpfs          787M  1.6M   785M   1% /run
/dev/sda5       17G   16G     0   100% /
tmpfs          3.9G     0   3.9G   0% /dev/shm
tmpfs          5.0M  4.0K   5.0M   1% /run/lock
tmpfs          3.9G     0   3.9G   0% /sys/fs/cgroup
/dev/loop0     411M  411M      0  100% /snap/wine-platform/74
/dev/loop1      91M   91M      0  100% /snap/core/6405
/dev/loop3     174M  174M      0  100% /snap/spotify/34
/dev/loop2      98M   98M      0  100% /snap/docker/321
/dev/loop4     128K  128K      0  100% /snap/league/22
/dev/loop5     411M  411M      0  100% /snap/wine-platform/88
/dev/sda7       47G  4.0G    41G    9% /home
/dev/sda1      246M   31M   226M   13% /boot/efi
tmpfs          787M    0    787M    0% /run/user/1000
tmpfs          787M  4.0K   787M    1% /run/user/110

how can i solve this?

Answer 1

17G is usually not enough for the root partition of Ubuntu or its derivatives if you want to install some bigger software. I'd say with 25-30G you're on the safe side.

Temporary Solution to be able to log in again:
From terminal, try to remove some bigger software packages you don't need right now:

sudo apt remove some-big-software

Also it should be safe to remove files in /tmp/ and /var/log/ to gain some space to be able to login again

sudo rm -Rf /tmp/*
sudo rm -Rf /var/log/*

Solution:
Start from a Live USB and use gparted to allocate some space from sda7 to sda5. See here.