Thunderbolt cable no longer delivers a signal to my monitor after Tahoe 26.1 update

Question

Thunderbolt cable no longer delivers a signal to my monitor after Tahoe 26.1 update

Thunderbolt cable no longer delivers a signal to my monitor after Tahoe 26.1 update.

I use a MacBook Pro with an M2 Pro. Recently updated to Tahoe 26.1. I use a 40" LG UltraWide monitor and I also use a Arzopa 15" portable monitor. Both are connected thru a Thunderbolt cable. My 40" also delivers power to my laptop. I also have an Anker USB-C docking station. I have gone thru the steps of unplugging all cables and restarting my laptop.

After the update, my 40" UltraWide can no longer find a signal from the Thunderbolt cable. I unplugged everything and tried it as a standalone monitor, none of the ports would deliver a signal, but it still delivers power. To get my setup to work the same way it did before the update, I now have to use the Thunderbolt for my portable monitor and HDMI for my UltraWide, but I also have it use the original Thunderbolt cable to keep my laptop charged. I also have to be sure to plug in the HDMI before the Thunderbolt for my UltraWide because it doesn't auto-switch from detection.

Is there a fix for this? A settings change I can make?

MacBook Pro (M2 Pro, 2023)

Posted on Nov 16, 2025 10:47 AM

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Answer 1

Top-ranking reply

neuroanatomist

Level 9

57,069 points

Nov 16, 2025 10:57 AM in response to JayAfterForty

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. The Thunderbolt cables that ship with many displays are not high quality.

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Answer 2

Nov 16, 2025 11:06 AM in response to neuroanatomist

Thanks for the reply. Do you by chance have a recommendation on a high quality cable? It's driving me nuts whenever I move between rooms and then back to my office.

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Answer 3

Nov 16, 2025 11:21 AM in response to JayAfterForty

Something from Belkin, Cable Matters or Monoprice, or anything sold by Apple (well, not the Charge Cables).

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