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macrumors newbie
Original poster
Oct 13, 2013
I have a brand new 2018 MacBook Pro 15 inch and I downloaded macOS Mojave. For some reason, brightness is still at full. When I try to adjust it, the bars tick down but brightness does not change. After exiting the brightness adjustment and going back in, it shows the brightness as full again. Has anyone else encountered this issue? I've tried resetting SMC, NVRAM, and PRAM and nothing did the trick. Please help!


macrumors newbie
Jul 20, 2018
It's definitely has to due with macOS Mojave. I just bought a 2018 15" Pro as well and I'm experiencing the same issue. I'm trying to downgrade to High Sierra which is now seemingly impossible. I used my iMac to download High Sierra from the Mac App Store and created a bootable external hard drive to try and reinstall High Sierra. I tried booting from the external HD to begin the install and I get a circle with a cross in it (almost like a stop sign). I've tried the recovery tool and the MacBook Pro ends up just looping thru the recovery process but never installs High Sierra. Anyone have any suggestions?


macrumors regular
Jan 27, 2018
One should never install a beta on your main machine, you are looking for trouble.

There's a reason why it's called a beta. You will find bugs, issues and machine stopping errors.


macrumors newbie
Jan 19, 2016
Install Brightness Slider from the App Store. It's free and will temporarily fix your issue.


macrumors newbie
Mar 29, 2020
Wow Brightness Slider fixed the problem on my iMac. I am a bit shocked because i was assuming it was just using the F1 and F2 keys but it doesn't. Somehow it can control the brightness even though i can not control the brightness through the System Preferences. What a quick fix, so happy!!!
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