The Systemd Bug That Nobody Wants to Own

TL;DR: There’s a namespace bug affecting Ubuntu 20.04, 22.04, and 24.04 servers that causes random service failures. It’s been reported since 2021 across systemd, Ubuntu, Fedora, and Red Hat trackers. Most reports are either expired or labeled “not-our-bug.” Only a reboot fixes it. If you’re running Ubuntu servers and have ever seen this in your logs: Failed to set up mount namespacing: /run/systemd/unit-root/dev: Invalid argument Failed at step NAMESPACE spawning: Invalid argument Main process exited, code=exited, status=226/NAMESPACE Congratulations. You’ve encountered one of the most frustrating bugs in the Linux ecosystem — one that’s been bouncing between the kernel and systemd teams for years with no resolution. What Happens Random systemd services — including critical ones like systemd-resolved , systemd-timesyncd , systemd-journald , and your own custom services — suddenly refuse to start. The error mentions “mount namespacing” and “Invalid argument.” Restarting the service doe