13

After update macOS from Ventura 13.0 to 13.1 my Macbook Air (M1, late 2020) does not detect my external monitor connected with Type-C (LG 35WN75C-B)

It was working right before the update.

I've tried to:

  • Restart system
  • Plug off monitor, restart system, and plug it on again
  • Press "Detect Displays" button after all those actions.
  • Change monitor Display port version from 1.4 to 1.2 (and reboot system again)
  • Power off monitor and turn it on again after system restart as described in this question

Any ideas how to fix it?


Update: After switching USB-C Cable to Apple's original one my Macbook now able to recharge battery from monitor, but still doesn't see it.

7
  • How are you connecting? HDMI? DisplayPort?
    – Allan
    Commented Jan 12, 2023 at 4:49
  • 1
    @Allan directly with Type-C cable
    – Yaro
    Commented Jan 12, 2023 at 5:06
  • I forgot to ask why you downgraded your monitor’s firmware
    – Allan
    Commented Jan 12, 2023 at 5:44
  • @Allan I've seen this topic on MacRumors and thought that it might help. Anyway I've changed it back to v1.4
    – Yaro
    Commented Jan 12, 2023 at 5:59
  • Where exactly, in MacOS Ventura, does one find the "Detect Displays" button?
    – threed
    Commented Apr 5, 2023 at 21:59

7 Answers 7

6

I've been struggling with this problem for a while, but this worked for me: Turn off monitor. Unplug HDMI cable from USB-C to HDMI adapter. Unplug USB-C to HDMI adapter from Macbook Air. Plug adapter back in to Mac. Restart Macbook. Turn on monitor. Plug HDMI cable into adapter.

I think there's some state hanging around in the HDMI adapter and/or Ventura that needs to be reset.

3
  • I guess you're right about these observations. I was struggling with the same trouble after upgrading to Ventura 13.2.1. I have two external monitors connected to my Mac and the device stopped detecting both of them after upgrading. Commented Feb 19, 2023 at 22:49
  • This seems to have solved my problem for me, thanks for saving me from the headache of fiddling around with the HDMI cable...
    – 92lexus
    Commented Nov 4, 2023 at 16:26
  • Thanks! In my case I was using some Dell USB-C to HDMI/RJ45 adapter from my previous laptop. Worked perfectly until today. Directly connecting the screen to the macbook's HDMI port still worked, but no longer through the adapter. Did your steps and is working again! (macbook m3 pro with sonoma here)
    – Matthias
    Commented May 23 at 8:22
2

I’ve been battling with the same problem and after reading posts about this issue I believe it’s MacOS Ventura’s fault. No solutions I found helped so I’ll try to downgrade my macOS as a last resort.

Check out this detailed thread: Upgrade from BigSur to Ventura macbook pro not detecting external monitors and TVs

2

I've resolved it. I have no idea how does it work, but here is what I did:

  1. Connected USB Hub
  2. Plugged USB-C cable into it
  3. Monitor connected
  4. Remove USB Hub
  5. Connected cable directly
  6. Monitor connected again

It's pretty strange behaviour


Update: after I've connected this monitor to my PC I'm unable to connect monitor to Macbook again. So - problem was not resolved


UPDATE 2: Solution that resolved issue:

  1. Completely shut down monitor.
  2. Remove cable
  3. Shut down macbook
  4. Wait for some time (In my case it was about 8 hours)
  5. Plug in cable to macbook
  6. Turn on macbook

This solution described multiple times at different forums. But in my case I had to wait more than 5-10 minutes while my MB is off. And I still have no idea how does it work

2
  • Was the monitor detected when plugged in the USB Hub before the update? Commented Jan 12, 2023 at 7:17
  • @DavidAnderson It was. But it was a months ago - even before 13.0 update.
    – Yaro
    Commented Jan 12, 2023 at 7:45
2

Use USB-C power only.

If you plug in another power adapter (e.g. MagSafe) then it disables some of the functionality of the USB-C port. This includes disabling the Option key for Detect Displays on the Display settings page in System Preferences.

2
  • Ok, so you are saying that if the laptop is getting power only from USB C, Detect Displays will be accessible via the Option key, right?. But if power is coming from MagSafe (or whatever other non-USB source), then Detect Displays will not be available. This seems like an odd choice on Apple's part: why can't I connect my charger and an external display?
    – Paul
    Commented Jul 28, 2023 at 21:17
  • Most USB-C monitors will power the laptop as well, so the MagSafe is unnecessary. It does seem an odd choice that you can't config it when both are plugged in at the same time. Commented Jul 30, 2023 at 3:16
1

Your monitor should support USB-C without having to go through that "dance" shutting down, disconnecting, waiting, and reconnecting. Per the specs page on LG's website:

INPUT
OUTPUT
HDMI Yes x 2 DisplayPort Yes x 1
USB Type-C Yes Headphone Out Yes
USB-C (DP Alternate Mode) Yes USB-C (Data Transmission) Yes
USB Down-stream Yes x 2

Below are some items you want to check. I can't tell you how many times (from extensive professional experience) replacing a simple cable fixed troublesome issues. It's always good to start with quality connections.

  • Get a USB-C cable that supports DisplayPort Alt Mode.
  • Try a USB-C to DisplayPort cable and connect to the DisplayPort interface (not USB-C Alt). In my experience, DisplayPort has always been a reliable technology.
  • Ensure you're running the latest firmware of your monitor. LG Software Downloads.
  • Verify this problem doesn't exist on a different computer (like a Dell laptop). If it does, then this is definitely a monitor issue and not macOS. This will help you focus your efforts going forward.

When purchasing cables/adapters, always go for reputable brands like StarTech, Cable Matters, Belkin, Cable2Go, Pluggable, etc. They cost more, but their quality is much higher than the no-name discount brands. Many times you may purchase what seems like a decent cable, but to save costs, they remove support for certain features.

Despite all the capabilities ... it is important to note that not all USB-C products support USB-C’s full functions.

Source: BenQ USB-C FAQ

Hopefully this will get you working or at least pointed in the right direction of a solution.

1

I'm using a Lenovo USB-C Dock (Gen2) and a few weeks ago my 2020 MBP13 wouldn't recognise the attached 34" Samsung Display. Whilst attaching a 2018 ThinkPad (running Fedora 38) just recognised the Display as expected...

Just now I realized that I also had an issue with charging from that Dock a while ago before it started to refuse to recognise the display!

As I read all those suggestions of attaching USB-Hubs and so on I attached my USB-C charger before I connected the docking cable and bada boom the display gets recognised again!

So attaching other USB stuff to get it to trigger the display recognition definitely works!!!

-1

I came across an article on how to fix macOS Ventura/Monterey not detecting external monitor.

Apart from the method you have taken, it also recommends that you do the following:

  1. Allow Accessories to connect to USB-C connections.
  2. Boot into Safe Mode.
  3. Update the hub driver or software.
  4. Change screen resolution.
  5. Update your Mac.
  6. Disable 'Automatic graphics switching'.
  7. Downgrade macOS

Maybe you can try one of them to get your issue resolved.

1
  • This is basically the list the topics covered in the linked page, how does this relate to the specific problem described in the question?
    – nohillside
    Commented Feb 7, 2023 at 15:59

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