Kernel

Systemd timers can fall silent after a kernel upgrade

When a new kernel lands, the kernel‑specific modules and initramfs changes can break the ExecStartPre or ExecStart scripts that a timer relies on.
The result? A timer that never fires, or that fires with the wrong environment.

Below is a step‑by‑step guide to diagnose and restore a broken timer, with security‑aware notes and trade‑offs you’ll run into in a production or homelab setup.

When a kernel upgrade silently breaks your network

Kernel upgrades are usually painless, but on a few systems they can trigger a cascade of “carrier lost” messages that make the interface drop and come back up repeatedly. The messages are buried deep in the system journal, so you may not notice them until the network flaps start causing outages. This post shows how to locate those hidden messages with journalctl, correlate them with real‑world symptoms, and apply a fix that keeps the interface stable.