External Monitor Issues Since 13.2 Upgrade

My Dell 49"ultrasharp gets into a mode like this after a software upgrade at times, the only fix is to unplug the AC cable, wait a bit and plug it back in. The power switch on the monitor doesn't fix it. Just had this happen to me today after 13.2.1 update on my MacBook Pro

Hi pdokeegan,

Welcome to Apple Support Communities. We understand that you're having an issue with your connection to your external device after upgrading your MacBook Pro to macOS 13.2. We'd like to help.

Have you restarted your MacBook Pro since you noticed this issue appearing? Sometimes a simple restart can help with issues like this. Give that a try to see if that helps:

Restart your Mac

On your Mac, choose Apple menu  > Restart.

If you don’t want app windows that are open to reopen when your Mac restarts, deselect “Reopen windows when logging back in.”

Is your Mac set up to go to sleep or wake at a specific time? Knowing this can help you start to isolate this issue:

Specify sleep and wake settings for a Mac laptop

1. On your Mac, choose Apple menu  > System Settings, then click Battery  in the sidebar. (You may need to scroll down.)

2. Click Options on the right, then do any of the following: 

* Put hard disks to sleep: Turn on “Put hard disks to sleep when possible.”

* Update your system while it’s asleep: Click the pop-up menu next to Enable Power Nap, then choose an option.

See What is Power Nap?

* Allow your Mac to wake briefly so users can access shared services (if applicable): Click the pop-up menu next to “Wake for network access,” then choose an option.

See Share your Mac resources when it’s in sleep.

Let us know how that goes.

Take care!

https://www.youtube.com/watch?v=4P6naBVT0O0 This is how I fixed it. I also needed to adjust the screen size from 1920x1080- thats what my monitor allows to like 1200 something. Then I needed to adjust the hertz from 75 to 60.

Yep, that always seems to do the trick apparently...

But needing to pull out the AC outlet of a monitor after a macOS update doesn't seem really normal to me.

Already tried turning it of and on again for both the MacBook and the Monitor.

I tried everything -- unplugging the monitor's AC cord many times, restarting the computer (also putting it to sleep), following everyone's suggestions as to what to do at settings -> display (though often the monitor was not detected). Finally, I unplugged both ends of the cord connecting my Acer monitor from my 2021 M-1 Macbook Pro and a minute later plugged them both in, and the monitor lit up for the first time in days. I think the cable I'm using is a Thunderbolt 3 and it's going into the monitor's Audio jack. I was told that an HDMI cable might be more reliable, so I may end up getting one if this fix is only temporary. I've never posted anything but this was so frustrating i wanted to put this up in case it can help anyone else.

The trick that fixes it for me is to unplug the monitor power cable from the AC outlet, wait and plug back in. The power switch on the unit is not enough to reset it.

Here is how to fix it! https://www.youtube.com/watch?v=4P6naBVT0O0

After updating to 13.2.1 my Dell 49" inch monitor stopped working using a USB-C cable.

Sir, you made my day. That did the trick.