That's because chromium_presubmit was migrated to luci, but the entry wasn't removed from the milo configs, so Milo still thinks it exists and happily displays the last known builds from a month ago.

LUCI migrators are supposed to remove these entries after migrating a builder, so we may need to reinforce the instructors to highlight this (since it doesn't cause breakage, but does cause a lot of confusion, it's often missed).

If increasing visibility of instructions don't work, we can start thinking about automated solutions.

Also FTR the migrated location is here:

https://ci.chromium.org/p/chromium/builders/luci.chromium.try/chromium_presubmit

Sure, but that just solves the problem of "chromium_presubmit shows up when viewing tryserver.chromium.linux console". It doesn't solve the problem of "clicking 'chromium_presubmit' on https://ci.chromium.org/buildbot/tryserver.chromium.linux/chromium_presubmit/649004 results in a 404".

the builder was deleted on buildbot. perhaps, all we can do it to redirect to the LUCI counterpart in this case.

Can we run a script over the config to see what builders are dead and remove them? We should visually distinguish stale builders as well but it's not great that we have a bunch of dead links on prod.

Ryan, you had some scripts for making sure we had all buildbot builders listed in luci-milo.cfg - could that be modified to find what needs cleaning here?