Caps Lock switches language instead of typing capitals

Why it happens

When you add a second keyboard language, macOS can use a quick tap of Caps Lock to swap between them. With that on, a tap changes language instead of turning on capitals. It's handy if you switch languages all day, and puzzling if you only wanted capital letters.

How to fix it

1. Open the Apple menu, choose System Settings, and click Keyboard in the sidebar.

2. In the Text Input section, click Edit… next to your input sources.

3. Turn off Use the Caps Lock key to switch to and from ABC, then click Done. If your list uses another layout, the option names that one instead of ABC.

   Keyboard›Text Input›Edit…›Use the Caps Lock key to switch to and from ABC

4. Press Caps Lock and type a few letters. You should get capitals, and the key's light comes on if it has one.

Still not fixed?

1. Want to keep the language switch? Leave the option on, and press and hold Caps Lock for a moment to turn capitals on. A quick tap still changes language.

2. To switch languages another way, use the Select the previous input source shortcut, Control-Space unless you've changed it.

   Keyboard›Keyboard Shortcuts…›Input Sources›Select the previous input source

3. If Caps Lock does nothing at all, open Modifier Keys and check that Caps Lock isn't set to another key or No Action.

   Keyboard›Keyboard Shortcuts…›Modifier Keys›Caps Lock (⇪) Key

4. If the language changes when you haven't touched Caps Lock, turn off Automatically switch to a document's input source in the same Edit… sheet.

   Keyboard›Text Input›Edit…›Automatically switch to a document's input source

5. If Caps Lock still won't type capitals, try another keyboard. If that one works, the key may be faulty, which is a hardware repair: contact Apple Support or a repair shop for a built-in keyboard.