MacOS 13.4 Ventura - External Monitor no longer detected. Worked until the update to 13.4

I am using Mac Studio M1 and I had the same issue after updating to the latest MacOS Ventura 13.4.

My monitor setup: 2x Benq monitors. One connected via HDMI and one via USB-C. USB-C connection is affected.

I tried this and it worked for me.

1. Disconnect the USB-C monitor from either the monitor or Mac. Keep the HDMI monitor on.
2. Go to System Setting.
3. Go to Display.
4. Select any other resolutions. Return to your preferred resolution.
5. Re-connect the USB-C to the monitor.

This worked for me.

If you only have one monitor, I guess you have to try other connection/options. I know that HDMI works in this update.

Currently known issue: When web browser is in full screen in either monitor, the other monitor is blacked out. I think this is still unresolved. I do not know how to feedback to Apple and I don't have time for that. Hope Apple can patch it up soon.

Best Regards.

IG: nehpyh

I took my new Mac Air upgraded with 13.4 to a trade show expecting to mirror and use an external monitor to playback a video I created. The external monitor worked the first time I tried this via USB-C to HDMI, but it would suddenly drop out every few seconds. I suspected a cable issue or HDCP, but changing to a brand new cable(s) did not work. I spent HOURS trying to get the thing to work. The computer could see the monitor and the monitor could see the computer. I tried every toggle and permutation in system settings (stupid iphone like crap now). Suddenly, it worked - the video played for several hours and all was well. But I had to shut down after the show ended for the day. Next day the issue reappeared right off the bat. External monitor would come on, show me the laptop desktop and then go black or green. I spent hours hair pulling and trying all the same permutations and IT.NEVER.WORKED.AGAIN!

It is OBVIOUSLY HDCP. (Is my desktop now copy protected from my own stuff? This reminds me of how Apple refused to pay for firewire and suddenly my entire library was unplayable! No, I haven't forgotten that Apple!) I have had Apple computers since 1995 - and I never hated them as much as I do now for their total incompetence and disregard for the video professionals who kept them alive before Gates injected them with enough money to keep them from sinking. BOOOOOOO!!!!!!

I have a Dell U4919DW that completely stopped working altogether after updating to 13.4, at least with the USB-C cable. I also have an Apple Studio Display, and that actually still works.

would love a fix for this asap Apple 😎

or some kind of workaround

So I have been having some trouble too because until the update I was able to connect my M1 MacBook Pro to 3 displays. But now Apple's website reads that you can only have one extra display:Connect one or more external displays with your Mac - Apple Support

"You can connect one or more external displays, depending on your Mac.

• For Mac computers with the Apple M1 Chip: You can connect a single external display to your Mac. Docks don’t increase the number of displays you can connect. On a Mac mini with M1 chip, you can connect a second display to the HDMI port. See the Apple Support article Mac computers with Apple silicon."

So that may be a contributing factor as well like it is for me. I hope it goes back to the way it was!

I just tried that and it didnt work. So annoying. Shouldve just left it as OS X 13 because everytime you update sh*t like this happens. Ridiculous Apple!

For the record. I have a M1 Macbook Air connected via USBC to a LG 4k USBC port

I actually wound up resolving this by unplugging the monitor for a few minutes and then plugging it back in. It seems like the update process put the monitor into some state that it couldn't recover from - a state that simply turning the monitor off and on again with the power button doesn't help with (the power button apparently doesn't fully reset the monitor).

The monitor resumed working as normal after being unplugged for awhile. I vaguely recall having to do something similar after a previous macOS update, so maybe this issue isn't specific to Ventura.

I was able to get my secondary monitor working again.

My current setup is a Mac Mini M1 2020 with a TwelveSouth StayGo USB-C hub. The primary monitor is using the Mac Mini's HDMI port while the secondary monitor is plugged into the USB-C hub's HDMI port.

Not sure which combination of things helped, but here's what I tried:

• I toggled the Displays Have Separate Spaces option under Settings > Desktop & Dock as suggested here: MacOS 13.4 Ventura - External Monitor no … - Apple Community
  • The option was already toggled on for me so I toggled it off, then logged out and back in. Then toggled it back on and logged out and back in again.
• I deleted the plist file and rebooted, as suggested here: https://discussions.apple.com/thread/254875167?answerId=259082968022#259082968022
• Lastly, I unplugged the USB-C connection between the StayGo hub and the Mac Mini and plugged it back in. Then I unplugged and plugged in the secondary monitor HDMI connector on the StayGo hub.
  • That brought the second monitor back online

I first had an M1 Macbook Pro which worked fine connecting to, two, 49 inch Samsung Monitors. I decided to upgrade to the M2 Macbook Pro Max. It worked find for about 1.5 days, until I got the notice to upgrade to 13.5. As soon as I did, all stopped working. The only time they worked was when I would unplug and plug-in around 20 or so times. Then, I would unplug and plug into the other ports, naively, hoping they would now work. They didn't. I was on the phone with Mac support for that instance, around 4 hours. They ended up telling me to take the machine to the Apple Store. I did just that and the team at this store, as my machine was only a few days old, provided me with a new machine. Soooooo....I took the machine home and set it up. Then.....about 8 hours later, it prompted me to update the machine again. I had not yet put together the issues and the fact it was the update that was bricking my machine from connecting external monitors. Soooo...again, on a call with Apple the next morning. I was then told it was not their issue and for me to call Samsung as it HAD to be Samsung and not their glorious machine or software. Sooooo....I was tired of the games. I took the machine back and then ordered a decked out Lenovo Legion, with an NVIDIA 4080 and 32GB of ram. It should be here in a few weeks. I failed to mentioned that I tried all of my other machines and the ports worked fine. I even tried an iPad Pro, and it worked fine. I will be taking a nice little break from the Apple ecosystem. If all goes well with my Windows machine, I will see if I ever come back.

"You can type with one or more fingers, depending on your Mac

• For Mac computers with the Apple M1 Chip: You can type with a single finger. Docks don’t increase the number of fingers you can use. On a Mac mini with M1 chip, you can use a second finger for typing on the external display. See the Apple Support article Middle Fingers with Apple silicon."

In System Settings->Desktop & Dock, under Mission Control, make sure that “Displays have separate Spaces” is CHECKED. Logout and login again to activate this feature, and the problem should be solved.

I have a similar issue after upgrading to Ventura 13.4. I'm connecting my M2 laptop to an external display using USBC. The display works fine but the peripherals (keyboard and mouse) connected (with USB) to display stopped working after the upgrade. Before the upgrade, they all were working fine.

Anyone has an idea as to how to fix it?

JediJ1207 wrote:

So I have been having some trouble too because until the update I was able to connect my M1 MacBook Pro to 3 displays. But now Apple's website reads that you can only have one extra display:Connect one or more external displays with your Mac - Apple Support Mac

"You can connect one or more external displays, depending on your Mac.

For Mac computers with the Apple M1 Chip: You can connect a single external display to your Mac. Docks don’t increase the number of displays you can connect. On a Mac mini with M1 chip, you can connect a second display to the HDMI port. See the Apple Support article Mac computers with Apple silicon• ."

So that may be a contributing factor as well like it is for me. I hope it goes back to the way it was!

i was also facing same issue once i updated my Mac 1 actually am a video editor and i have to connect my system with 2 to 3 displays more.

So it finally works! Designers need to go back and reconsidering the UX/UI.

a “tiny” modal appears to ask you to connect the external monitor! I overlooked it completely, navigated away!

Either give 2 points of entry as is, or:

1. make a bigger modal and disable navigating away
2. allow the user to give permissions to connect via the display settings.

I was just able to troubleshoot this successfully, so in case it's helpful to others, let me document my situation. First of all, I should note that I was able to use my exact hub/dock and external monitors without issue on my MacBook Pro (M1 Pro chipset) until about 2-3 months ago. I don't know what OS X version it was running at that time, but that's when I noticed that one of my USB-A devices connected to the hub (a Leopold mechanical keyboard) could no longer be detected by my computer until I connected it (via an adapter to make it USB-C) directly to the machine. Then suddenly, my other USB-A accessory (Razer Kiyo Pro webcam) and my external displays (see below for makes and models) also were no longer detected. I have since verified the failure on another hub (Anker 777 Thunderbolt Docking Station) as well as my wife's work hub (model info not available at this time, but it was a third manufacturer).

My home setup (where problems were first discovered)

• Macbook Pro (M2 Max chipset; also confirmed with M1 Pro and M2 Pro chipsets as having same problems)
• Kensington SD5700T Thunderbolt 4 hub/docking station
• 2x HP VH240a external displays (HDMI connections)
• 2x Anker HDMI-to-USB-C adapters (for the monitors, so they could use the T4/USB-C ports on the Kensington hub)
• Other USB-A peripherals mentioned above
• Apple Magic Trackpad (connected via bluetooth but charged via a USB-C port on the Kensington hub)

The setup that allowed me to successfully fix the problem

• Same Kensington hub and M2 Max Macbook Pro
• LG 27BL85U-W external display (HDMI plug)
• 1x of the Anker adapters mentioned above for the external monitor connection

I'm still not *exactly* sure what fixed it all, but the problem seemed to be that, upon plugging my hub into the Macbook Pro (via a USB-C cable), an Allow/Deny dialog was popping up saying something like "Would you like to allow this Kensington hub access to your computer?" However, on my home setup, this dialog was popping open and immediately closing itself before I could even read what it said. When I went to my local Apple Store for a Genius Bar appointment to troubleshoot it though, and used their external test monitor (the LG one I mention above), the dialog didn't auto-close for some mysterious reason. So I was able to Allow the hub on my machine and, when I got back home, it worked flawlessly with my home setup!

What is super puzzling about all of this is that I had already tested the hub at home with no monitor plugged in at all, which I assume would have triggered the Allow/Deny dialog properly, but it didn't. It's possible that the dialog won't trigger without a device attached to the hub that you're trying to connect, but I'm not sure. Ultimately, the most likely explanation to me is that my HP monitors weren't communicating through the hub in a way that Ventura/Sonoma OS X could understand to properly trigger the Allow/Deny dialog and using the LG monitor worked better.

I hope this helps those of you still struggling out there! The key takeaway: try a bunch of different external displays to see if this confirmation dialog is the real culprit. Once you Allow, you should be able to switch back to your preferred setup and have it all work again.