LG ultrawide monitor does not work after update macOS Tahoe 26.1

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Level 1

6 points

LG ultrawide monitor does not work after update macOS Tahoe 26.1

I have a Mac mini connected to an LG UltraWide 5 K monitor. Everything went fine after the last macOS update (Tahoe 26.1). That is, the display was correctly detected via USB-C. It works in the previous version of Tahoe 26.01 and the prior version of macOS.

After the update, the display is not recognized via USB-C. I am still using the same USB-C cable and connecting to the same USB-C port on both the Mac mini and the monitor. If I connect via HDMI, the Mac mini detects the external display correctly, but it does not show all the resolutions displayed when I connected via USB-C.

Also, I tried connecting the display to my MacBook Air via USB-C (with the same cable), and everything worked fine.

It must be an issue with the new update. An issue with the resolutions, since some resolutions do not appear.

Mac mini, macOS 26.1

Posted on Nov 9, 2025 9:31 AM

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Answer 1

Top-ranking reply

neuroanatomist

Level 9

55,893 points

Nov 9, 2025 9:40 AM in response to mjcobo

macOS has become progressively less tolerant of video data packet loss due to sub-par cables. There have been several reports of setups that worked in Sequoia not working in Tahoe, with nothing changed but macOS.

Best recommendation at this point is to try a new cable. Be sure to use high quality cables – HDMI should be labeled Ultra or Premium, USB-C cables should be rated for high-speed data transfer, etc. Also,cables should be as short as possible (≤1 m for most cables, <0.5 m for Thunderbolt 5 cables). That random cable you found in a drawer might or might not work.

FWIW, I have an LG 5K:2K ultrawide and it’s working fine with my M4 MBP on 26.1.

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Answer 2

Nov 9, 2025 10:04 AM in response to mjcobo

Agree it seems odd. But several others here have reported that as a fix. I use a short (0.5 m) TB3 cable to a Stone Pro dock, and a 1 m TB3 cable from that to the display.

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Answer 3

mjcobo Author

Level 1

6 points

Nov 9, 2025 9:58 AM in response to neuroanatomist

Hello,

Thank you for your quick reply. I will try to buy a different cable, but I don't know if this is the problem. I connect the Mac mini to a Mac Studio Display with my USB-C cable, and it works.

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