(This post is also a test of whether the mailing list is working.) GTALUG's server's filesystem filled up: little disk space left. I discovered this when I tried to do "apt update; apt full-upgrade". The second step failed, saying that /var/cache/apt/archives had no room. This means that / has no room because / contains that directory. Tip: "df /some/path" will tell you how much space is used on the filesystem containing /some/path and it will tell you the mount point of that file system. I wandered around the filesystem, doing: sudo df -s * | sort -n This command lists things in the current directory, and their sizes, largest last. (It skips things with names starting with ".".) Pretty soon, I found that most of the space was taken up by /var/cache/apt/archives after all. This kind of surprised me. Googling got me to others with this problem. The advice: sudo apt autoclean That gave back (only) 3% of the disk. That directory was still way too big. Most of the space was taken by 35 versions of gitlab-runner. I have no idea why we need multiple versions. Violence is sometimes the answer. sudo apt clean That left only 32% of / used. Note /var/cache/apt/archives is only a cache. If the system wants any of these, it should be able to find them in a repo.