Hello,
after upgrading my MacBook to macOS Catalina I can't connect external displays. Minutes before installation it was all properly working. It seems like MacBook doesn't detect them at all.
Anyone has similar issue? Any hints?
The displays are not Apple (HP, Asus).
Maybe this might point you in the right direction.
I fixed my full time pink screen issue, here is the solution. I think it might apply to your issue as well. For those of you without working screens, I suggest finding a screen that does work temporarily, and installing Teamviewer, or some other free program to remotely log into your machine. After doing so, connect the nonworking screen, start the computer, and log in remotely, then follow the steps 1-5 below. you will have to switch back to the working screen for the steps 6-15
The reason it is having an issue, is after the update, the signal being sent is YCbCr instead of RGB like your monitors are expecting. Some people with panels like mine will get pink, others likely get no signal recognized. This script works by setting up a profile for your specific monitor, and having it be forced to be RGB, if you connect it to another model monitor with the same issue, this process will need to be repeated for that monitor as well.
Hope this helps everyone! if you have issues look in the comments on the script page, the author is active.
My machine is a Mac mini (2018) i7 64GB 1TB. My monitor is a 28 inch Hannspree HF289H monitor
DisplayLink is a product that consists of some software to create a Screen Buffer in RAM, and a stunt-box that contains some special chips that can accept the screen data forwarded over a mundane interface like USB-2, and simulate a Legacy display interface at the far end. It has been bundled into dozens of other products like Multi-port docking stations.
DisplayLink considers it their "product" and you can certainly cast aspersions on how well it works and how well they are keeping up with the changes in MacOS, they never intended to "trick" anyone with it.
One solution has been to go to the displayLink web site and be sure to download current Driver software. Dock-makers have been awful about keeping you up to date.
I do agree that using a different interface or a converter on the computer-side of a dock is completely unlikely to yield success.
"Thunderbolt 3 cable from the MBP box"...
The MBP does not normally come with a Thunderbolt cable, so I have to ask: did you buy the cable separately from Apple?
Or did you assume that the cable that comes with your mac is a Thunderbolt cable?
The cable that comes in the box of every mac is a USB-C power cable; just because the connectors look the same, it does not make it a Thunderbolt one.
How is the display connected?
Does it work if you start in Safe Mode?
Did you try resetting NVRAM and SMC?
FWIW, I use my MBP every day with lots of different displays and projectors, connected via HDMI, Thunderbolt, VGA and I have yet to have any display fail to work since I installed Catalina last October.
My mac is older (2014), so no USB-C. It appears that most people who experience display problems have more recent macs with USB-C. Unfortunately I don’t have one of those.
This solution did NOT work for me.
Bought a Startech.com USB-C Adapter from Amazon namned: "USB-C to Mini DisplayPort Adapter - 4K 60Hz" and it did not change anything. Same result as before with the Apples USB-C adapter. Problem must be Catalina based and not hardware. Writing this so others can save their money and not try this or similar adapters to solve this problem.
For reference I use a MBP 13" (2018) + Apples Cinema display with a display port as external monitor, this worked just fine before installing MacOS Catalina...
2019 Macmini i7 confirmed loss of Usbc 2nd screen fixed by resetting Pram and did the SBC unplugging. Not sure if only needed to do Pram reset, but it worked, fixedvUSB C docking issue where I was losing a SSD drive intermittently also
Adapters at that link identify themselves as Mini DisplayPort to HDMI.
That low-cost adapter may not be adequate for displays with resolutions higher than 1920 by 1080p.
what model Acer display? what resolution?
How are they connected exactly? If with some sort of dock, which model?
If you open System Preferences->Displays, hold down option key and click Detect Displays, any effect?
Had this same problem today after upgrade and on my 2018 Macbook Pro resetting the SMC solved the problem.
Any chance this machine has an older software from displaylink?
Hi, I have the same issue. Sometimes the screen is detected and other times not - as tomasz228 describes. I use an HDMI cable from my Viewsonic VX2858Sml. I haven't found a fix and hope Apple sort it asap!
I wonder whether purging RAM may help as Boldvigil's response below.
I don't know if the cause and effect are there, but when I started this
morning, the monitor was not working. My "Clean Your Mac" updated to
Catalina and I ran it. Voila! After completion with no restart, my
external monitor suddenly appeared. Since "Clean MY Mac" cleans the RAM,
it might have been the problem.
tomasz228 wrote:
I tried plugging and unpluging several times and shutting down Mac. Nothing worked. Then on another Mac I just left it plugged in and after 30 min it lit up. When I connect and disconnect the screen doesn’t turn on immediately. The other Mac can’t even detect single external screen.
i can’t find any logic in how this works. Sounds like patch is needed.
Has anyone been successful with safe mode reboot?
I've been fighting with this problem since I upgraded my MacBook Pro a few weeks ago. The suggestions on this thread will fix it intermittently (reset SMC/NVRAM specifically) but none have been a consistent fix as they don't work every time. I tried the suggestion of purchasing CleanMyMac and it seams to have worked...for now. I know Luis Sequeira1 gave a pretty ominous reply to someone else's thread about this and I really don't want to install anything on my Mac that would hurt it...it's become the center of my livelihood. However; I did research and saw that the product was "Notarized by Apple to be free from malicious malware" (although...admittedly this is a comment from the vendor itself) so I took a chance and tried it this morning. For the first time in a couple of weeks I have access to both of my external HDMI monitors connected to my laptop via UBC-C. I really hope Apple comes out for a permanent fix for this soon.
Yes, I recognize the picture and meant no disrespect by my comment. I actually took it into consideration and held off on purchasing CleanMyMac because of what you said. However, I'm at my wits end with this problem and needed to try something new and this seemed to work. All I did was run the software as-is. It reported that it removed 4.01 GB of "System Junk" (whatever that means) and after a reboot both monitors came back online without a problem.
I have to tell that this system has serious issues when talking about ports and detecting what's connected. It was problem for macbook pro 2017/2018 highest tier, before Catalina and now it's impossible to work with.
DO NOT UPDATE if you work with external displays.
My mac is always connected with 4 usbc to charger, two DELLs (that are working fine for older macs) with usbc - displayport and one usb port for keyboard etc.
And everytime I disconnect mac from my displays and I do it several times a day, i have to restart system.. everytime cause then connecting displays are flickering, black screen whatever but it does not work.
Avoid new update for catalina. It wasnt good before, cause had trouble from time to time, but now it is always there
Sorry, no. Several people have reported that they had regained the use of their display by changing the cable. However I am still using my trusted 2014 MBP so I don’t have a USB-C equipped mac to test.
honeydew74 wrote:
I used a USB-C to thunderbolt adaptor that I used to use Lonovo Yoga laptop.
As far as I can tell, this HP portable display requires specific drivers, even in windows.
It connects via USB 3, which is something not natively supported in the OS.
There is no "thunderbolt" involved, but maybe you are not describing the adapter correctly.
USB-C uses the same connector as Thunderbolt 3. All ports in current macs carry both types of signals.
Your mac can can connect to several kinds of displays with the right adapters (Thunderbolt, USB-C, HDMI, VGA...)
In this case the adapter would be USB-C to traditional USB 3. It would require a driver. Maybe it will work with "displaylink" software.
I don't
External display not working after installing MacOs Catalina
