MacBook Not Detecting an External Monitor: First Fixes

Blank screen or no detected display?

Check whether the monitor shows its own menu. If its menu does not appear, investigate monitor power first. If the menu works, note whether macOS lists the display. These are different observations and help narrow the next step.

1. Simplify the connection

Apple recommends checking both ends of the power and video cables and testing without a hub or dock. USB-C shape alone does not tell you whether a cable supports your display’s video requirements.

1. Check the monitor’s selected input against the port you connected.
2. Connect one display directly, using a suitable video cable or adapter.
3. If available, try a known-working compatible cable. Change one component at a time.

2. Ask macOS to detect the screen

Reconnect the display and its power, or try putting the Mac to sleep and waking it. Save your work before restarting.

1. Open the Apple menu > System Settings > Displays.
2. Hold Option to reveal Detect Displays, then select it.
3. On an Apple silicon MacBook, approve the accessory connection if macOS asks and you recognize the display.

3. Check your exact MacBook limits

The number of supported external monitors and available resolutions depend on the exact Mac model and connection. Check Apple’s specifications for your model rather than assuming every MacBook supports the same arrangement.

1. Find your Mac model in About This Mac.
2. Compare its display support with your intended setup.
3. If testing with the lid closed, connect power and an external keyboard and mouse as Apple directs.

Still not working?

Test the monitor with a different compatible computer, or test the Mac with a different display. Record the Mac model, macOS version, monitor model, and the full cable or dock chain before contacting support. Update macOS and applicable monitor firmware using official instructions.

Frequently Asked Questions