After updating to Tahoe macOS 26.1, only the right side of my LG monitor lights up. I tried restarting the MacMini and restarting the monitor. Does this have anything to do with the software update? Is in no longer compatible with my monitor? Does the monitor need a software update? Is there a control setting I can check? I am not an expert so I am quickly getting over my head. Thank you for ideas.
Mac mini, macOS 26.1
That looks more like a problem with the 5K LG displays backlighting, than a problem with the M1 Mac mini.
To do some easy troubleshooting.
1) Test a different display or HDMI TV plugged into the Mac mini.
2) Test that LG display plugged into a different computer or game console.
“Is Tahoe compatible with my LG Monitor?
After updating to Tahoe macOS 26.1, only the right side of my LG monitor lights up. I tried restarting the MacMini and restarting the monitor. Does this have anything to do with the software update? Is in no longer compatible with my monitor? Does the monitor need a software update? Is there a control setting I can check? I am not an expert so I am quickly getting over my head. Thank you for ideas.“
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Troubleshooting External Monitor:
A. Try Mirroring the Home Screen:
That will mirror the Home Screen, and allow you to use it as if it were you laptop's screen. Note the "Dim Display is located above the 1 and the 2 keys of the keyboard.
B. View "Graphics/Displays" in System Information:
C. Reset the SMC and your NVRAM:
(Applies to Intel-Based Macs Only): Sometimes when changes are made to the system(i.e. Updates), system configurations (i.e. for Displays) become manipulated, technically. So, reset the SMC and NVRAM. Try performing each thrice. It may take sometime, being certain you have the time to perform these resets.
Do you see the issue if you select different screen resolutions besides the 2560x1440?
More detailed information is required.
What year model is the Mac Mini..?
see > Identify your Mac mini model - Apple Support
What model # is the LG external display..?
What cable connection are you using between the Mac mini and LD display..?
My mini was made in 2020. I am connected by a lightning cable (probably 1 generation). I don’t have a game console or TV that I can connect with a lightning cable. I may disconnect the LG monitor and take it to Apple genius to connect another device. If that doesn’t work, it was purchased evidently in 2020 with the mini, I assume it’s the monitor and look into replacing it. Thank you and everyone for all your assist when all else fails. It must be the monitor. It’s just funny that it worked perfect until the software upgrade and then stopped working. Properly.
A USB to Lighting cable is used for charging and syncing iPhones and iPads.
What you have there, is either a Thunderbolt 3/4 or USB-C to USB-C cable.
Again the best way to troubleshoot.
1) Test a different display or HDMI TV plugged into the Mac mini.
2) Test that LG display plugged into a different computer or game console.
“[…]Thank you for sharing your ideas. Do you have any other ideas before I reach out to Apple Repair? I reported the problem with downloading Tahoe to Apple already.“
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You are welcome.
Seeing “Automatically Adjust Brightness: Yes“:
I’m thinking this is doing this from power, along with the operating overruling this output. So, if an LG display does not work, then there might be a way in the macOS or third-party software to turn this off feature off. Being this all comes down to being half in brightness, this might all just go away.
Screenshot:
I tried steps an and B above, nothing changed.
I also went to system settings/displays, and I set “when connected to TV” to “ mirror entire screen”. Nothing changed. Are we started the computer? Nothing changed.
I still have the issue with only the right side of my display lighting up following the update to 26.1 Tahoe.
Thank you for sharing your ideas. Do you have any other ideas before I reach out to Apple Repair? I reported the problem with downloading Tahoe to Apple already.
Thank you
Is Tahoe compatible with my LG Monitor?
