Why Quick Look's Space Bar Stops Working After Karabiner or BetterTouchTool

BetterTouchTool: Spacebar as a Modifier

BetterTouchTool documents its own technique for making the spacebar act like a modifier key: hold Space, tap a letter, release Space, and BTT fires whatever action you assigned, the same pattern as "Command plus a letter" but built around the space bar instead. It works because BTT operates as a low-level event tap that sees keyboard input before the system delivers it to the focused app, which is exactly what lets it intercept a bare Space press meant for Finder's Quick Look.

The tool's own user community has documented the limitation directly: one detailed configuration guide on BetterTouchTool's official forum states plainly, "I have not found a way to block only the Spacebar with BTT," recommending a keyboard-response-speed workaround instead of a clean exclusion. Separately, and unrelated to any deliberate setup, BetterTouchTool shipped a real bug in versions before 6.176 (fixed February 10, 2026) where the space key "sometimes stopped working" specifically during drawing and mouse gesture recognition. If you're on an older build, updating BetterTouchTool alone may be the entire fix.

If you built the spacebar-as-modifier setup on purpose and want to keep it everywhere except Finder, BetterTouchTool's own documentation describes app-specific overrides: add Finder to the app sidebar, then either disable the global spacebar trigger for that app so it falls back to the default behavior, assign the action "Use Apple Default or Do Nothing" while Finder is frontmost, or scope it with a Conditional Activation Group. Any of the three stops BTT from eating the keypress specifically inside Finder.

Any Other Global Hotkey Tool Bound to Bare Space

Karabiner-Elements and BetterTouchTool are the two most common culprits because they both explicitly support remapping or capturing the bare spacebar with no modifier attached, which most macOS apps intentionally avoid registering as a global hotkey precisely because it collides with things like Quick Look. If you use skhd (a lighter, config-file-only hotkey daemon popular alongside tiling window managers like yabai) or Hammerspoon with a Lua script that binds a bare space event, the same conflict applies for the same reason: whichever process taps the keyboard event stream first wins, and Finder's own Quick Look handler runs later in that chain.

The fix is the same shape regardless of which tool is responsible: find the rule or script binding a bare Space with no modifier, and either remove it, add a Finder-specific exclusion if the tool supports one, or change the trigger to require a modifier key (Option-Space instead of Space alone) so it stops overlapping with Finder's own shortcut entirely.

Find It Without Guessing: HotkeyClash

HotkeyClash is a free, open-source (GPL-2.0) macOS menu bar utility built specifically to answer "what else is using this key combination." It scans three sources: the Accessibility API menu-bar shortcuts of every app currently running, Karabiner-Elements and skhd configuration files directly, and the macOS symbolic hotkeys property list that stores built-in system shortcuts like Mission Control and Spotlight. It requires macOS 14 or later, needs no account or internet connection, and collects no telemetry.

It's a genuinely useful first check, with one honest limitation: it reads Karabiner and skhd configuration files directly, so a spacebar rule built there shows up clearly. It cannot see inside BetterTouchTool's or Alfred's own private preferences unless that binding is also exposed as a normal app menu shortcut, which a spacebar trigger usually isn't. Treat a clean HotkeyClash scan as ruling out Karabiner and skhd specifically, not as clearing every possible tool.