MacBook Pro screen goes full brightness

Same. I did the NVRAM and SMC reset procedures. The brightness was still 100% ( 2019 iMac 27" ) .

I turned the brightness down to 50% and restarted my iMac to see if the setting would "stick", but no, it went back to 100% brightness, even before I logged in.

I didn't do the safe boot the first time. I did the SMC and NVRAM resets , and neither fixed the issue. However, I did a safe boot this morning, and that , at least for now, fixed the brightness issue.

I reboot my iMac twice since then to make sure that the brightness has stopped going to 100% , and it has.

My fingers are crossed that this is the end of the issue, but if it does reappear, I'll try doing just the safe boot to see if that is the magic bullet.

The issue should never happen, so I think Apple should still investigate it.

Hi AxeBox360.

Let us know the results.

I did try safe boot a few times. Not a fix for me. The problem re-appears on both MacBookPros with LG Ultrafine.

It's only a matter of when, not if. It may be on first restart. It may be the next day or after 4,5 or 6 restarts/Wake from Sleep.

Do let us know.

Small update. I returned my MacBook Pro 16" today at an Apple Store. It was less than 14 days since ordering, so no questions asked.

The Apple Store rep who helped me out indicated that it was a known issue amongst those working at the Genius Bar. No solution is available at this time.

S.

Appreciate the update. Not surprised.

I'm hoping a future update to Catalina will address this and am hoping those folks here on this discussion will be able to share their experiences with future upgrades :)

Same issue recently unfortunately on brand new MacBook Pro 16 inch connected to LG super fine 5K monitor (this is a new machine swapped out to replace previous one bought a month ago because the ambient light sensor wasn't working, I discovered!).

With the "Automatically adjust brightness" and "true tone" boxes unchecked, on power up either screen may come up at full brightness or a random setting. I've done all the things Apple support suggested i.e. resetting SMC, PRAM, booting up in safe mode etc...all to no avail. They have now booked the system into an Apple service centre to test it with other external monitors to see if the same issue occurs - I think I know what the answer might be having just discovered this discussion group this evening.

Like one of the other members on here, since buying the computer I have been spending more time and effort beta testing Apple's products, not using them as I should be - I discovered other issues with this Apple model as well that Apple engineers are now 'looking into' apparently.

Whilst you might expect some bugs and software issues with new systems, there appears to be a distinct lack of testing or quality control in some areas - having used Apple computers for nearly 40 years now, I can honestly say that this new machine has caused me more trouble and wasted a significant amount of my time on calls to Apple support than any of the previous systems I've owned combined.

I hope these issues can be resolved quickly...

Hi Hubhal.

Really appreciate you're adding your experience here. I'm very curious as to what the Apple Service centre says after they get back to you.

And I'm curious what other issues you're having (other than ambient light sensor) on the 16" MBP. As I mentioned, mine has been returned to Apple (the 14 day no question return policy was executed by Apple perfectly - kudos to them). It's likely I'd re-order it if once the problem gets fixed as any other current Mac is either too expensive or not powerful enough if portable!

I too am in my 40th year of using Apple computers and worked for a time - a long time ago - as a consultant providing Apple hardware to publishing companies.

Scroll down to the entry about LG bug:

https://daringfireball.net

Please keep us up to date here.

Thanks, Stephen

This issue is not limited to the 2016 MacBookPro and LG 5K Ultrafine. It's happening with the new Mac Pro and XDR monitor.

What's in common? Only guess I have is based upon both being driven by a Thunderbolt 3 video connection alone and both running Catalina.

I've also stated previously that I see the issue very on my 3 year old 15" MacBookPro w/TouchBar but very very infrequently. Prior to upgrading it to Catalina (to help diagnose my 16" MBPro) it *never* did the brightness thing. So again, TB3 video and Catalina on my old computer - but the interaction is far far less severe.

The issue is now also being discussed on Twitter thanks to John Gruber @daringfireball and John Siracusa @siracusa.

Also discussed by Lloyd Chambers on Mac Performance Guide https://bit.ly/2GgTdNR

And MacinTouch https://bit.ly/2TR63dV

And iMore https://bit.ly/38yJ6jK

Stephen

Axebox, could you please link us to the right location to post a bug report directly with Apple? It doesn't appear that they monitor or respond to this Apple sponsored discussion forum. Users only zone here, it appears.

I'm glad to hear that this particular issue is now getting properly reported and discussed in enough places that maybe it will be fixed. There are others that I would like to report.

Thanks

According to what I'm hearing it's pretty common.

I hope the next OS update will address it, but I'm not holding out on that as a sure thing.

Maybe someone will sign up for the beta program and try the latest 10.15.3 beta?

I need a faster Mac and want to re-purchase the MacBook Pro I returned...

Apple released Catalina 10.5.3 today (Jan 28 2020)

I'm travelling overseas today through Feb 8th.

If anyone on this discussion installs the upgrade and has feedback on the 100% Brightness Display issue please let us know.

Thanks!!!!

Stephen

Just updated to Catalina 10.5.3 - unfortunately this hasn't resolved the "full brightness" issue with this update having tested this again. In fact if the system preferences / displays windows are open showing the brightness slider levels for both MacBook Pro and LG 5K superfine display (in my case) - by just plugging and unplugging the external display into the MBPro you can see the brightness slider incrementing on its own on the MBPro screen.

This issue was escalated to Apple engineering by me last week as mentioned in a previous post but I haven't had a response as yet.

I updated to 10.15.3 on 28th January but still have same issue as reported in previous post. This update doesn’t appear to have addressed this or other reported issues such as dictation. Let’s hope there is another update soon...

I'm having the brightness issue as well on my 2 LG 5K's hooked up to my 16" MBP. However is anyone else having issues with the monitors not waking up after going dark or sleeping? Mine will sort of flicker back and forth and eventually I'll have to unplug both and restart the computer.

I've used these 2 monitors with my 2016 MPB as well as the 2019 16" MBP and the experience to this day as been anything but seamless. When they are working, which honestly is most of the time, they are beautiful. However sometimes I avoid unplugging them just because I don't know what I'll get when I plug them back in. Might work, might not and require a restart. I figured after 4 years these monitors would be better integrated into the Apple OS... guess not.

I can't really be much more specific. I updated to that software, and so far plugging and unplugging my monitor it has been holding the brightness setting. I've probably only done it 5 times so far, but before it would go full bright more than 1 in 5 tries. Another poster said the update didn't work for him, so we'll see. I don't know anything about the specifics of the update itself.