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Catalina 10.15.3: Dell monitor not recognized (2018 mini)

l have a 2018 Mac mini with the following monitor arrangement:


mini Thunderbolt 3 USB-C port -> Dell U2410 monitor (DVI input)

mini HDMI port -> Dell S2716DG monitor (HDMI input)


After updating to Catalina 10.15.3, when I wake the mini from sleep mode, the mini will at first recognize both monitors but after a moment will drop the Dell S2716 and go solely to the U2410. To get it to re-recognize the S2716 monitor, I have to unplug and re-connect the HDMI cable. (Ugh.)


Anyone here seeing similar monitor recognition issues with 10.15.3?

Mac mini, macOS 10.13

Posted on Feb 6, 2020 9:10 AM

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Posted on Feb 9, 2020 9:54 AM

Hi Becky,


The monitor being unrecognized (until the HDMI cable was pulled and reconnected) happened twice right after the 10.15.3 update, but not since. Hopefully it has somehow self-resolved. That may seem to suggest it was a loose HDMI cable, but that had been working solidly for months prior, and the monitor issue immediately corresponded to the OS update.


Anyway, things look good right now. Thank you for the troubleshooting link, and for your time and help.


Have a great day!


Bill L

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Question marked as Top-ranking reply

Feb 9, 2020 9:54 AM in response to raina_b22

Hi Becky,


The monitor being unrecognized (until the HDMI cable was pulled and reconnected) happened twice right after the 10.15.3 update, but not since. Hopefully it has somehow self-resolved. That may seem to suggest it was a loose HDMI cable, but that had been working solidly for months prior, and the monitor issue immediately corresponded to the OS update.


Anyway, things look good right now. Thank you for the troubleshooting link, and for your time and help.


Have a great day!


Bill L

Feb 9, 2020 8:56 AM in response to Bill L

Hello Bill L,


I understand your issue to be that your Dell monitor is not being recognized by your Mac Mini after updating to Catalina. I am happy to help you with this.


Take a look at the article below for some helpful troubleshooting steps.

Get help with video issues on external displays connected to your Mac


Let me know if that worked for you.

Thank you for using Apple Support Communities.

Take care!

Catalina 10.15.3: Dell monitor not recognized (2018 mini)

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