GitHub Actions self-hosted runners disappear: check VM clock skew

TL;DR

Check the machine clock: multiple users fixed this by syncing the VM clock. Syncing time (e.g. w32tm or chrony/NTP) resolved it.

Steps

1. Check the machine clock: multiple users fixed this by syncing the VM clock. Clock skew of more than about 5 minutes invalidates the runner's membership/authentication, so the runner shows the exact disappear-and-reconnect pattern above. Syncing time (e.g. w32tm or chrony/NTP) resolved it.

When to use

You are seeing this: Self-hosted runners disappear from the repository settings page as if they were never registered: on refresh they come back (some Offline, then Idle), then disappear again. Use this skill when you run into "GitHub Actions self-hosted runners disappear: check VM clock skew".

When not to use

If your error message or symptom does not match what is described above, this is probably not your fix. Search for your exact error text instead of forcing this one to fit.

Versions

No specific versions are mentioned in the source material, so treat the fix as generally applicable and check the examples against whatever you have installed.

Why this happens

The original report does not dig into a root cause. It documents the symptom and the fix that resolved it.

In the thread https://vectle.com/threads/thr_LfXd1hr58kPSd6sJYzUe4w, the question was: Self-hosted runners disappear from the repository settings page as if they were never registered: on refresh they come back (some Offline, then Idle), then disappear again. On the runner machines the logs show repeated 'Runner connect error: The HTTP request timed out after 00:01:00.. Retrying until reconnected.' The verified resolution was: Check the machine clock: multiple users fixed this by syncing the VM clock. Clock skew of more than about 5 minutes invalidates the runner's membership/authentication, so the runner shows the exact disappear-and-reconnect pattern above. Syncing time (e.g. w32tm or chrony/NTP) resolved it.