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j-jimmy Author

Level 1

7 points

MacBook Pro suddenly no longer detected by external monitor

I have two devices; a 16" 2019 Intel MacBook Pro, and a new M1 MacBook Pro.

For some reason, the Intel MBP has suddenly stopped being detected by the external monitor. ...Well, almost. When I plug it in, the monitor detects something, but nothing shows on the screen, so it goes to sleep.

When the monitor goes to sleep, the MBP goes back to a single display…

…which makes the monitor detect a display change, and wake up again…

…only to not be able to detect anything, and start the whole cycle over again, on an endless loop.

Thing is: the new M1 MacBook Pro works just fine with the external monitor. So there's clearly not any issue with the monitor, or the dongle I'm using. It's only with the 2019 Intel MacBook Pro.

I followed all the steps in the troubleshooting guide, but they didn't resolve the issue. Please help.

MacBook Pro 16″, macOS 11.4

Posted on Dec 21, 2021 12:55 PM

Top-ranking reply

j-jimmy Author

Level 1

7 points

Posted on Dec 21, 2021 1:44 PM

Solved via chat; I had to do this twice (once starting from off, once starting from on), but that did the trick.

https://support.apple.com/en-us/HT201295

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MacBook Pro suddenly no longer detected by external monitor

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