Linux Error Fixes
Each page covers one error: what it says, why it happens, and the exact commands that fix it.
- ext4: No space left on device, but df -h shows free space
What you see Writes fail, but df -h insists there is room: $ df -h /var Filesystem Size Used Avail Use% Mounted on /dev/sda2 59G 41G 15G 74% /var $ …
- Docker: permission denied on /var/run/docker.sock
What you see docker ps fails immediately with permission denied on /var/run/docker.sock, while sudo docker ps works. Nothing is wrong with the daemon. …
- nginx 502: upstream prematurely closed connection
What you see The browser gets 502 Bad Gateway. error.log contains upstream prematurely closed connection while reading response header from upstream, …
- systemd: Failed to Start Service (exit code 203/EXEC)
What you see systemctl status myapp reports a failed unit, and the journal shows status=203/EXEC. The service never reaches your application code, so …