After updating to Sequoia 15.2 and 15.3, an extended monitor turns back.

My MacBook Pro m3 pro got updated to latest "stable" version of macOS 15.3.1, and since then my external display connected via HDMI cable no longer works. My display detects that it has been connected to a HDMI source, but nothing on screen. My Macbook's display option doesn't list the external display at all (But still detect it somehow in terms of screen resolution changing).

Tried reset, restart, creating new user account and all other suggested troubleshooting.

Same display with same HDMI cable works on this MacBook if I connect using a USB c to HDMI adapter.

Interestingly same display, same cable and MacBook also works in Recovery Mode (shutdown MacBook, power on and keep holding power butting when it prompt for Startup options, select Recovery mode). There display works fine via HDMI connection, So its definitely apple's update breaking it.

We tried replicating this case successfully on 2 other macbook also (all using different brand of external displays). Connected with Apple support too, who suggested regular troubleshooting steps and finally scheduled a call with senior advisor.

PS: deleting the plist file in ~/Library/Preferences/ByHost/com.apple.windowserver.display.... won't make any difference.

It's really a big issue for someone using multiple display and relying on Apple for stable update.

This is unbelievable --- happened to me this evening on two different computers. On my MacMini M4, turns out that while it booted fine, it somehow disabled both displays. I pinged it from another machine and noted it seemed to be up, so ssh'd into it and that worked too, but rebooting didn't help. I then physically unplugged both monitors and plugged them back in again and then everything worked.

On my wife's M1 Mac Mini, I saw a similar problem - rebooting didn't help at all. Eventually, I just held down the R while power cycling, expecting to get into recovery mode but somehow that actually took me to the regular setup for "updating" and everything worked.

No idea what Apple did here but their Q/A is just getting worse all the time. It's really quite disconcerting. If I hadn't been there, my wife would have been completely stuck!

pasitpon wrote:

I’m reporting an issue with my extended monitor after upgrading to Sequoia 15.2 and 15.3.

The monitor and MacBook detect the signal when connecting via HDMI, but the screen remains black. Restarting both devices and checking for loose connections haven’t resolved the problem.

The current stable release of Sequoia including bug fixes, security updates is macOS 15.3.1

Keep your Mac up to date - Apple Support

Keep your Mac up to date - Apple Support

if no resolve—

To be proactive you can file a bug report / submit your Apple Feedback here: Product Feedback - Apple

For me issue appeared with version 15.3.1 (latest stable update). So having up to date system might not be a helpful in this case.