MacBook Air M2: No external display after macOS Tahoe 26.5.1

Question

AshishShenoy Author

Level 1

4 points

MacBook Air M2: No external display after macOS Tahoe 26.5.1

MacBook Air M2 not detecting external display after updating to macOS Tahoe 26.5.1

Device

MacBook Air M2 (Apple Silicon)

macOS Version

macOS Tahoe 26.5.1

External Display

LG Ultrawide Monitor

Connection

USB-C to HDMI

Issue

Immediately after updating to macOS Tahoe 26.5.1, my MacBook Air M2 stopped recognizing my external monitor.

The exact same setup (MacBook, monitor, cable, and adapter) was working perfectly before the update. No hardware changes were made.

When I connect the monitor:

The monitor's backlight turns on, indicating it detects a physical connection.
However, the Mac does not detect the display at all.
The monitor eventually shows no usable display output.
The external display does not appear in Display Settings or System Information.

Troubleshooting already performed

I have already completed the following without success:

Restarted the Mac multiple times.
Shut down both the Mac and monitor completely before reconnecting.
Power-cycled the monitor.
Disconnected and reconnected all cables.
Tried different USB-C ports on the Mac.
Verified that the LG monitor works correctly with another device using the same monitor.
Verified that the issue began immediately after updating to macOS Tahoe 26.5.1.

Since the monitor functions correctly with another source and nothing else changed except the macOS update, this appears to be a software regression rather than a hardware failure.

Additional Information

I have also noticed multiple users reporting similar external display detection issues after recent macOS Tahoe updates, particularly involving USB-C to HDMI connections.

Request

Could Apple please investigate whether macOS Tahoe 26.5.1 introduced a regression affecting external display detection over USB-C to HDMI?

If this is a known issue, it would be helpful to know:

Whether Apple is actively investigating it.
If there is a temporary workaround.
Whether a fix is planned in an upcoming macOS update.

Thank you.

MacBook Air, macOS 26.5

Posted on Jun 26, 2026 8:56 PM

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Answer 1

Top-ranking reply

v1v3km

Level 5

6,272 points

Jun 26, 2026 10:33 PM in response to AshishShenoy

Hi AshishShenoy,

Thank you for such a detailed and well-documented report. Based on your description, this does look like a software regression introduced in macOS Tahoe 26.5.1 affecting USB-C to HDMI display detection, which several users have noticed.

Since you've already covered the basics, let's try some deeper steps:

1. Reset the Display Preferences:

- Go to System Settings → Displays and check if the external display appears there at all, even if not shown on the desktop.

- If nothing shows, try holding the Option key and clicking "Detect Displays" if the button appears.

2. Reset NVRAM/PRAM:

- Shut down your MacBook Air.

- Turn it back on and immediately hold Option + Command + P + R for about 20 seconds.

- Note: On Apple Silicon Macs (M2), NVRAM resets automatically on every boot, but a manual shutdown and cold boot can sometimes still help flush cached display settings.

3. Check for a display driver/kernel extension issue:

- Open Terminal and type: log show --predicate 'subsystem == "com.apple.iokit"' --last 5m

- Look for any display-related errors around the time you connect the monitor. This can help confirm it's a software issue.

4. Try a clean display connection test:

- Boot your Mac into Safe Mode (hold the Power button on startup, then hold Shift when you see the boot options screen).

- Once in Safe Mode, connect your monitor. If it detects in Safe Mode, it strongly confirms a macOS software-level conflict.

5. Submit Feedback to Apple:

- Since this is a potential update regression, I'd strongly recommend using Feedback Assistant (feedbackassistant.apple.com) to file a bug report.

- Include your macOS version, device model, cable type, and monitor model. The more users report it, the faster Apple can prioritize a fix.

As a temporary workaround while waiting for a patch:

- Some users have found that connecting the HDMI cable before waking the Mac from sleep (instead of while awake) can sometimes trigger detection.

- You could also try using a USB-C hub or dock with dedicated HDMI output instead of a direct cable, which sometimes bypasses the affected driver path.

Hope one of these helps in the meantime. If the Safe Mode test confirms it's macOS-related, definitely report it to Apple via Feedback Assistant so it gets addressed in the next update!

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