MacOS 10.15.1 - After installing, every time I reboot my iMac my screen is set to the maximum brightness. I can adjust it in system preferences, but I have my screen calibrated to a specific brightness for photography. I have "Automatically Set Screen Brightness" UNCHECKED so it shouldn't make any changes. Any ideas how to keep the brightness set where I had it when I shut down.
iMac Line (2012 and Later)
iMac booting at full brightness - FIXED.
Thanks to Birkhoff92. This link (https://support.apple.com/en-us/HT201295) tells how to reset the memory. In my case it was as easy as:
The computer does boot with the display appearing to go to full bright. However, as it continues to boot the brightness returns to where I had set it prior to shut down.
Hope this helps
You need to restore SMC https://support.apple.com/it-it/HT201295
I've had this happen since updating to Catalina on my iMac. I have found that if I briefly put my hand up to the camera area, where the ambient light sensor is, the brightness comes down to the right level. Not ideal but easier than going through the preferences menu each time! And yes, I have a second monitor connected.
OSX version 10.15.4 seems to have fixed mine! That was a long wait!
I've had this issue for a while when resuming my Macbook Pro from sleep - I generally never shut it down. I think I might have resolved it by turning off Night Shift.
Although, "avoided" would be a better word than, "resolved". I will miss having Night Shift enabled, and also auto-brightness, which I had to disable because it was changing the brightness far too much as the sun came out and went back behind a cloud.
So sorry this didn’t work. I also have a USB-C to HDMI (Apple brand) connecting my second monitor. All auto brightness options are off and my monitors are calibrated as I use this computer for photography. If I unplug the desktop for 15 seconds before starting or I unplug the second monitor prior to start I usually get a brightness that I shut down with. It seems like quite a few people are having this issue. Perhaps Apple can weigh in here and let us know if a fix is on it’s way.
Someone has mentioned blocking light sensor next to camera seems to fix it. It seems to work.
Perhaps taping over said sensor could be a work around? Granted youd loose the auto brightness feature.. haven't tried myself yet :p don't have tape around right now
The 10.15.4 seems to fix it. Doesn't it?
I have a similar issue since the most recent upgrade to 10.15.1. Every time my Macbook Pro (2018)'s screen goes to sleep, when I wake it back up the screen is at full brightness. The usual controls in system preference doesn't seem to have an effect. I can manually change it back to a more reasonable brightness, but the next time the screen goes to sleep due to inactivity and wakes up it is at full brightness again. Will Apple please confirm that this is an issue?
I have a web cam cover covering my camera and sensor. Open or closed there is no difference. This appears to be a symptom of a second monitor attached. As a photographer the brightness is important. It takes about 15 minutes to calibrate a monitor AFTER it has been on for a while. The auto brightness is off, but I have found that at times, for no reason, it is switched on.
I'm having the same issue with my 27" iMac. Apple case 100952587736. I too am a photographer who calibrates my monitors. Having the system reset to 100% brightness on wake or restart is a huge issue for me. Resetting PRAM, SMC, disconnecting all monitors and peripherals, and even wiping the hard disc and reinstalling the OS has had no effect on this issue. Starting in November 2019, a month before my warranty was up, I've spent countless hours and enormous amounts of lost productivity on this issue with Apple with no resolution in sight. My iMac has spent 10 days at the Genius Bar, where they saw the problem but had no fix. I was assigned to a senior Apple phone support person, who was initially very helpful but no longer responds. Her initial guess was a macOS bug that would be fixed at some point. That was two updates ago and still no resolution. We are now four months into this issue and I'm pulling my hair out. I've been a loyal Apple customer for 33 years, and I want my computer fixed or replaced. And I want it now! The silence from Apple on this issue is deafening. I expect more.
Through experimentation, this only seems to happen if I have an external (HDMI) display connected. It did start with the latest OS update.
Same issue since 10.15.1 - it is only happening when I have an external HDMI monitor connected (using the Apple USB-C adaptor)
Any known fix?
It appears the latest update quietly fixed this issue. Three days and a few starts and numerous wake-ups and no issues.
I disabled Nightshift and thought that helped but no. With Nightshift off and "Automatically adjust brightness" unchecked, I've had two instances in the last hour of my MacBook Pro self-changing to full brightness.
macos 10.15.1 boots with screen at full brightness
