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Brightness of external display changes on its own even though "automatically adjust brightness" is off

I have a Macbook pro running Ventura and an LG UltraFine external display. I routinely calibrate the LG display using Colorite. Before calibration I check the display brightness and it is always set to the max. I need to manually adjust it back to the correct setting before doing the calibration. Next time I do to calibrate.. samething! Sometime since the last calibration the brightness has been set to maximum, which means at some point calibration became meaning less. "Automatically Adjust Brightness"is off, yet this is still happening. How can I prevent the brightness from changing on it's own?

MacBook Pro 15″, macOS 10.15

Posted on Oct 9, 2023 9:40 AM

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Question marked as Top-ranking reply

Posted on Oct 9, 2023 10:40 AM

It could be a damaged temporary cache or swap file for the system.


Give this a try: boot into Safe Mode according to How to use safe mode on your Mac and test to see if the problem persists. Reboot normally and test again.


NOTE 1: Safe Mode boot can take up to 3 - 5 minutes as it's doing the following; 

• Verifies your startup disk and attempts to repair directory issues, if needed

• Loads only required kernel extensions (prevents 3rd party kernel/extensions from loading)

• Prevents Startup Items and Login Items from opening automatically

• Disables user-installed fonts 

• Deletes font caches, kernel cache, and other system cache files


NOTE 2: if you have a wireless keyboard with rechargeable batteries connect it with its charging cable before booting into Safe Mode. This makes it act as a wired keyboard as will insure a successful boot into Safe Mode.


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1 reply
Question marked as Top-ranking reply

Oct 9, 2023 10:40 AM in response to DGS1

It could be a damaged temporary cache or swap file for the system.


Give this a try: boot into Safe Mode according to How to use safe mode on your Mac and test to see if the problem persists. Reboot normally and test again.


NOTE 1: Safe Mode boot can take up to 3 - 5 minutes as it's doing the following; 

• Verifies your startup disk and attempts to repair directory issues, if needed

• Loads only required kernel extensions (prevents 3rd party kernel/extensions from loading)

• Prevents Startup Items and Login Items from opening automatically

• Disables user-installed fonts 

• Deletes font caches, kernel cache, and other system cache files


NOTE 2: if you have a wireless keyboard with rechargeable batteries connect it with its charging cable before booting into Safe Mode. This makes it act as a wired keyboard as will insure a successful boot into Safe Mode.


Brightness of external display changes on its own even though "automatically adjust brightness" is off

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