Fix · Firefox

Can’t share your screen from Firefox: warnings, black windows and macOS permission

Sharing a screen from Firefox can be held up by Firefox’s own safety warning, by an old Firefox on a new Mac, or by macOS never having given Firefox permission to record the screen.

What you are seeing

You try to share or present in a call in Firefox and get a warning, an empty or black window, a message from macOS — or the other people simply see nothing.

The likely causes, most common first

Work down the list; most people find theirs in the first two.

1. Firefox warns you before sharing a window

  1. If a Firefox window is on screen when you share, Firefox shows a warning first. On a meeting site you trust, you can go ahead.
  2. To avoid it, share a single app window, such as your slides, rather than the whole screen or a browser window.

Mozilla: “Firefox will warn you not to share when a browser window is visible on your screen unless you trust that website.” — support.mozilla.org/en-US/kb/screenshare-safety

2. An old Firefox on macOS 15 or later

  1. Firefox 131 and earlier used a way of sharing the screen that Apple has retired, and newer macOS shows a warning about it every month.
  2. Update Firefox: open the Firefox menu, choose About Firefox, and let it install the latest version.

Mozilla: “To stop seeing the warning and ensure screen sharing works smoothly, just update Firefox to the latest release.” — support.mozilla.org/en-US/kb/screen-sharing-warning-macos-15-sequoia

3. macOS has not let Firefox record the screen

  1. On a Mac, open System Settings → Privacy & Security → Screen & System Audio Recording and switch Firefox on. Quit and reopen Firefox when macOS asks.

Apple: “You can decide which apps and websites are allowed to record your screen and audio.” — support.apple.com/guide/mac-help/control-access-screen-system-audio-recording-mchld6aa7d23/mac

4. Firefox is only allowed the sound

  1. macOS can give an app permission for audio alone. If the people in the call see a black rectangle, check that Firefox is allowed to record the screen and not just the sound.

Apple: “You can allow apps to record both your screen and audio, or just your audio.” — support.apple.com/guide/mac-help/control-access-screen-system-audio-recording-mchld6aa7d23/mac

5. You are sharing more than you meant to

  1. Sharing the whole screen shows every notification, tab and window that appears while you share. For most meetings, pick the one window you mean to show, and close anything private before you start.

Mozilla: “Screen sharing can be risky if you share a browser window or your whole screen with websites you don't trust.” — support.mozilla.org/en-US/kb/screenshare-safety

Every quote above is from Mozilla’s and Apple’s own help pages, read on 10 November 2026. Something changed? Tell us.

Other Firefox problems

Microphone not workingFirefox remembers a yes or no about your microphone for each website, and can refuse every new site at once — so a call that cannot hear you is usually a saved Block somewhere.Camera not workingIf your video is black in a Firefox call, look at Firefox’s saved answer for that site first, then at whether the computer lets Firefox near the camera, then at what else has it open.Transcript missingA Google Meet transcript is saved to the organiser’s Drive, only starts from a computer or an Android phone, and waits for the host to join on the web.Recording missingGoogle Meet saves recordings to the organiser’s Drive, only records from a computer or an Android phone, and stops by itself after eight hours.Notes or summary missingGoogle’s automatic notes need an eligible plan, a meeting of about fifteen minutes or more in one supported language, and somebody from the host’s organisation to start them.Breakout rooms missingBreakout rooms in Google Meet need an eligible Workspace edition and a host on a computer, and Google never records what happens in them.

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