A keyboard shortcut stopped working on a Mac: finding what took it

9 October 2026 · 6 min read

A keyboard shortcut that suddenly does nothing on a Mac is rarely a broken key. Far more often, something else has claimed the combination first: a macOS feature, a menu bar app that registered it as a global shortcut, or a setting that changed what a key sends. The keypress goes to whoever claimed it, and the app you are looking at never hears it.

The checks below run from quickest to slowest.

Find out how far the problem reaches

Before changing anything, answer two questions.

Does the shortcut fail in every app, or only one? Try it in two or three apps. If only one app is affected, the cause lives in that app: a menu item was renamed in an update, or a setting inside the app changed its keys. Open its menus and read what each command now shows beside it.
Does the key itself register? In System Settings, Keyboard, click Edit next to Input Sources and turn on “Show Input menu in menu bar”. Then choose Show Keyboard Viewer from that new menu. Each key lights up on the on-screen keyboard as you press it. If a modifier never lights up, the problem is hardware or a remapping, not a clash.

Check whether macOS already uses it

macOS keeps its own shortcuts in one place: System Settings, Keyboard, then the Keyboard Shortcuts button. The list on the left has sections for Mission Control, Input Sources, Screenshots, Spotlight, Services, Function Keys, Modifier Keys and App Shortcuts. Go through the ones that might overlap and look for your combination. When two of its own entries share a combination, macOS marks them with a small yellow warning triangle.

The usual collisions:

Control-Space, once you have added a second keyboard language. It switches input sources, which takes it away from editors and launchers that wanted it.
Control with the arrow keys, which Mission Control uses to move between desktops.
Command-Space, which belongs to Spotlight. Command-Space does not open Spotlight on a Mac covers the reverse case.
Shift-Command with 3, 4 or 5, the screenshot keys.
Services, where installed apps can add entries that carry shortcuts of their own.

Untick the macOS entry you do not use, or double-click its shortcut and press a new one.

Look for a menu bar app holding it

Clipboard managers, screenshot tools, launchers, window tools, dictation apps and meeting apps all register global shortcuts so they work from anywhere. Whichever app registers a combination first receives every press of it, and macOS does not tell you which app that is.

To find the holder:

Quit menu bar apps one at a time, testing the shortcut after each. Most have a Quit command in the menu that opens from their icon.
Check System Settings, General, Login Items (Login Items & Extensions in recent versions of macOS) for apps that start themselves at login and run without a Dock icon.
If nothing turns up, try a test account from System Settings, Users & Groups. If the shortcut works there, the clash comes from something that starts in your own account.

When you find the culprit, change the shortcut in that app’s settings rather than uninstalling it.

Function keys, the Globe key and remapped modifiers

Three settings change what a key sends, and each can make a shortcut look broken.

Function keys. On a Mac keyboard, the top row controls brightness, volume and media by default. A shortcut that uses F5, for example, needs Fn held as well, unless you turn on “Use F1, F2, etc. keys as standard function keys” under Keyboard Shortcuts, Function Keys.

The Globe key. In System Settings, Keyboard, the setting labeled “Press” with a globe symbol decides whether that key on its own changes the input source, shows emoji, starts dictation or does nothing. If it changed, habits built around that key stop working.

Modifier Keys. Keyboard Shortcuts, Modifier Keys lets you swap Caps Lock, Control, Option and Command, separately for each keyboard. Choose the keyboard from the menu at the top. A swap made for an external keyboard, often to suit a Windows layout, can leave Command where Option used to be, and then every shortcut feels wrong. Restore Defaults puts it back. Using a Windows keyboard on a Mac without going mad explains the swap that does make sense.

Secure input, and shortcuts that stop for a while

When a password field has focus, macOS stops other apps from watching the keyboard, so nothing can record what you type there. Terminal’s Secure Keyboard Entry, in the Terminal menu, does the same whenever Terminal is in front. Tools that act on keys as you type, such as text expanders and key remappers, go quiet while that protection is on.

If shortcuts come and go, look for a login page with the cursor in its password box, or Terminal with Secure Keyboard Entry ticked. Click out of the field or quit the app, and try again.

Shortcuts you added yourself

App Shortcuts, in the same Keyboard Shortcuts window, lets you give any menu command a shortcut of your own. It matches the command by its exact menu title, so it stops working when an update renames the item, even slightly. The ellipsis is a common catch: “Export…” in a menu is one character, which Option-Semicolon types, not three periods. Open the app’s menu, copy the title exactly as written, and set the shortcut again.

Use combinations nothing else wants

Most clashes come from the same crowded territory: Command or Control with a letter, perhaps with Shift. Holding Control, Option, Shift and Command together is different, because almost no app uses all four at once. A key that sends all four is often called a Hyper Key, and shortcuts built on it rarely collide with anything.

Trill adds one. Once you switch the Hyper Key on in its Shortcuts screen (it starts off), Caps Lock sends Control, Option, Shift and Command together with whatever key you press next. Tapped on its own it sends Escape by default, or does nothing, or still toggles Caps Lock. Any shortcut can run an action everywhere or only in apps you choose. If another app already holds a shortcut you pick, Trill says so and names the running app that may hold it, which answers the question this whole post is about. Hold the Hyper Key for a moment and a cheat sheet shows every shortcut that works in the app in front.

Trill needs macOS 14 Sonoma or later and asks for Accessibility permission so it can press keys for you. It is free for 24 hours with every feature, then $29 once. One caveat applies to any Hyper Key: macOS keeps a few four-modifier combinations for itself (all four with the period key starts a system diagnostic report), so try a new combination once before you rely on it.

Questions

Can I see a list of every global shortcut on my Mac? Not in one place. macOS lists its own in Keyboard Shortcuts, and each app lists its own in its settings. There is no system-wide register you can browse, which is why quitting apps one at a time is the dependable test.

A shortcut works on the built-in keyboard but not on an external one. Why? Modifier Keys settings are stored per keyboard, so the external one may have Command and Option swapped. Select it in the Modifier Keys menu and check.