Why do Macs ask you to press random keys when connecting a new keyboard?

What’s going on?

Ever been greeted by a small, baffling macOS dialog asking you to “press the key next to left Shift” and thought—what now? macOS is trying to figure out one simple but stubborn fact: which physical keyboard layout you plugged in. There are three common hardware families — ANSI (US), ISO (Europe) and JIS (Japan) — and they differ not just in where Enter sits, but in the extra keys shoved around the Shift keys. Because a plain USB or Bluetooth keyboard can't reliably tell the host its exact key placement, Apple asks you to press the neighbors of the left and right Shift to disambiguate layouts. Primitive? Maybe. Clever? Absolutely.

Why it matters

Press the wrong key and most of the time the consequences are cosmetic: the on‑screen visual layout or a few special characters might look off, and you can still pick the correct input language. But Japan is a special case — a JIS keyboard can have different legends even in English mode, so selecting the right hardware layout affects which symbols actually come out when you type. It has been reported that non‑typing devices — credit‑card readers, 2FA dongles, and other peripherals that masquerade as keyboards — can trigger the same dialog, which explains some of the head‑scratching.

Why Apple hasn’t fixed this (and why it’s still annoying)

Apple’s own keyboards reportedly don’t trigger the prompt because the hardware reports vendor and model IDs and macOS already knows their physical layouts. Third‑party keyboards? The vendor/model field is a wild west — many identify as “unknown,” so building a perfect fingerprint database is impractical. The dialog’s wording could be friendlier, and it sometimes breaks basic UI expectations, sparking a tiny moment of panic for users who just wanted to type. Still — as clumsy as it looks — it’s a pragmatic solution to a surprisingly hard problem. Sometimes the old‑school trick is the least bad option.

Sources: aresluna.org, Hacker News