Monterey 12.4 broke my external monitor connection

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Level 1

8 points

Monterey 12.4 broke my external monitor connection

MBP 13, 2019, 4 Thunderbolt ports. I was using it very successfully with 2 external monitors - Sony C24F390 and Acer H236HL - connected with HDML adapters and sometimes with an Anker USB Hub.

After updating from 12.2.1 to 12.4, my MPB will recognize only 1 monitor at a time. I have tried all the official and unofficial fixes I can find - resetting SMC and NVRAM, various tricks with unplugging and plugging in the monitors and/or cables - nothing has worked so far. I can get either display to work, but not both at the same time. I am using 2 separate adapters in separate ports. Whatever combination of cables and adapters I try will work on both displays but the Display settings can only see one at a time.

Any one have any additional suggestions?

MacBook Pro 13″, macOS 12.4

Posted on Jun 23, 2022 10:13 AM

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Answer 1

Top-ranking reply

Luis Sequeira1

Level 9

73,452 points

Jun 23, 2022 11:03 AM in response to jmckean

AFAICT, this is a configuration that is supported in your mac, and it should just work.

You confirm that it is a 2019 MBP, and NOT an M1 mac, right? (The M1 MBP only supports 1 external display).

You have already done a good work in troubleshooting this.

I can think of two possibilities: either some bug was introduced in 12.4, or some conflict with some third party software.

Did you ever install "DisplayLink"? If you did, you may need to update it.

Please run Etrecheck and post its full report here. Use the "additional text" button and paste the report into the text box.

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Answer 2

jmckean Author

Level 1

8 points

Jun 28, 2022 5:49 AM in response to Luis Sequeira1

Here is a weird update. I had a project for another client and I decided to use my personal Macbook Air. So I put the MBP to sleep and put it on a shelf for about 4 days. It was not plugged into a power supply. When I came back to it this morning, intending to do as Luis suggests, both external monitors came on without a fuss. I assume there was something in a volatile memory somewhere that all the resets didn't touch. or maybe . . . oh who knows. Anyway, I am back in business even if I have not added anything useful to the de-bugging process. I will return if the problem recurs.

The M1 only supports 1 external. ****, my company wants to "upgrade" me. Nothing is ever simple.

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Monterey 12.4 broke my external monitor connection

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