Level 1

37 points

External Monitor Issue After macOS Sequoia 15.1.1 Update

Hi everyone,

After updating my MacBook Air M2 to macOS Sequoia 15.1.1, I’ve encountered an issue with my external monitor. I connect my ViewSonic monitor via an HDMI-to-Type-C cable. The monitor works for about 5 seconds after being connected, then the screen goes black.

Interestingly, the monitor is still detected in the display settings, and I can even move the cursor into the display area—but nothing is visible on the screen.

Here’s what I’ve tried so far without success:

Adjusting the resolution and refresh rate.
Booting in Safe Mode.
Resetting display profiles.
Rebooting the system.

To rule out hardware issues, I tested the same setup on my MacBook Air M1. Before the update to macOS Sequoia 15.1.1, it worked perfectly. After updating, the same problem occurred.

However, I tried connecting to a Samsung external monitor, and that worked fine.

Has anyone else faced similar issues or found a solution? I’d appreciate any guidance or suggestions.

Thanks!

MacBook Air, macOS 15.1

Posted on Nov 26, 2024 8:50 AM

Top-ranking reply

rtpinzon

Level 1

14 points

Posted on Aug 11, 2025 6:40 PM

Hi all,

Last week I updated macOS to version 15.6 (24G84) and it seems that Apple has finally solved the issue with my monitor (Dell P2721Q).

I’ve been using it every day and the monitor hasn’t flickered yet.

It’s quite frustrating that it took more than eight months to get this issue resolved, and there’s still no RCA or any explanation for the problem, even though I had an open ticket with them through AppleCare+. Their last message to me, over two months ago, was that they didn’t know what was going on and that I would have to wait.

During this time, I tried multiple versions (including unstable ones), sent the machine to Apple for more than a week, and spent a couple of dollars on new cables and adapters.

I really hope that the issue does not appear again in a future release.

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177 replies

matsch57

Level 1

26 points

Dec 1, 2024 4:15 AM in response to MessyDuck

Really mysterious, I'll report in the next few days.

I just checked the refresh rates: the current adapter allows 30 Hz only

matsch57

Level 1

26 points

Dec 1, 2024 6:15 AM in response to MessyDuck

You were right, MessyDuck, but it took only a few hours until a new interrupt occurred. My very last adapter (dock for MBA) won't work better, I think...

Dec 1, 2024 7:43 AM in response to TxPomeroy

Curious, how many hours passed without this issue manifesting? Using the same docking station, I've had a full 8+ hours with no issues before it started manifesting again.

Dec 1, 2024 8:06 AM in response to MessyDuck

Curious, how many hours passed without this issue manifesting? Using a similar docking station, I've had a full 8+ hours with no issues before it started manifesting again.

Dec 2, 2024 12:57 AM in response to matsch57

I guess you should stay with the same hardware config for many hours in order to truly test it. This seems a software issue and completely random.

Dec 2, 2024 8:59 AM in response to jinesh1024

I have the same issue and I use an LG Ultra 4K connecting directly with a USB C cable (not using a dock) to a Macbook Pro.

arcyarcy

Level 1

14 points

Dec 3, 2024 6:28 AM in response to jinesh1024

I have the same problem also with an LG Ultra 4k and USB C

Dec 6, 2024 8:38 AM in response to MessyDuck

Mine happened immediately after update reboot.

kheowkul

Level 1

8 points

Dec 12, 2024 1:44 AM in response to arcyarcy

This fixed my issue with external monitor. Thanks!

HrBingR

Level 1

14 points

Dec 12, 2024 1:38 PM in response to Janusromanus

Sadly 15.2 didn't work for me; still an issue. Tried with usb-c adapter in one port and charger in the other, same result. Tried rebooting with external monitor connected, made no difference.

Dec 13, 2024 1:29 AM in response to Swkk

I haven't that issue until upgrading to 15.2 on my MacBook Pro M1. Now the system doesn't see my external monitor connected via DisplayPort. Very disappointed.

matsch57

Level 1

26 points

Dec 14, 2024 10:11 AM in response to Swkk

Again, I‘ve been wrong: 15.2. doesn't work reliable, too.

Dec 14, 2024 3:23 PM in response to Swkk

When can we expect a fix? It's already been weeks.

Dec 20, 2024 1:04 PM in response to drwatson5

Same here...and mine isn't that old either.

Dec 22, 2024 8:58 AM in response to Swkk

I have similar issues with my Thunderbolt 27" MC914LL/A monitor connecting to my Macbook Air M1 MGN63LL/A. Constantly flickers and goes black since updating to Sequoia.

External Monitor Issue After macOS Sequoia 15.1.1 Update