This question already has an answer here:
I visited Beer, Wine, and Spirits Meta, from the supercollider, and got this cryptic error instead of a list of questions:
Say what? I wasn't searching tags, as you can see from the URL.
This persisted through several refreshes over a few minutes, but as I finished composing this question the site returned to normal behavior. So the site isn't currently broken, but this error message seems misplaced so I'm still reporting it. This isn't the error we normally get for read-only mode, temporary server errors, or 404. Perhaps something is bubbling up from lower-level code without being caught, like maybe something having to do with favorite or ignored tags? (Of which I have none, by the way.)