2017 iMac keeps waking to login screen with graphics corruption

jmpage2

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Original poster
Sep 14, 2007
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I'm hoping this is not a hardware problem but it is starting to feel that way.

I have a 2017 27" i7 iMac running Mojave that has started misbehaving over the last few months.

I will be in another room of the house and notice that the iMac has woken itself from sleep. When I investigate I see that the Mac is sitting at the login screen but the colors on the login screen look wrong and the image is posterized.

If I log in (or it just logs me in automatically with my Apple Watch unlock feature) the display is completely normal... there is no graphics corruption in the desktop only the login screen.

Is this a known problem in software?
 

mikehalloran

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Oct 14, 2018
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You can download and run the Combo Updater but I prefer booting into the Repair Partition by holding Command r and reinstalling the OS. This will download and reinstall 10.14.5. It won't affect your data.

Apple will tell you to do this before anything else anyway.
 

jmpage2

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Original poster
Sep 14, 2007
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You can download and run the Combo Updater but I prefer booting into the Repair Partition by holding Command r and reinstalling the OS. This will download and reinstall 10.14.5.
Are there any other corrective options to attempt before a software reinstall is done?

Has anyone seen this problem? I will try to get a photo.
 

mikehalloran

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Are there any other corrective options to attempt before a software reinstall is done?
Nope. It's the first thing Apple will tell you to do if you call them. If you take it to the Genius Bar, they will do the same before anything else.
[doublepost=1561041297][/doublepost]If the App Store will let you download the complete Mojave installer, that works, too. Enter Mojave Install in the App Store and click on Get.

This doesn't always work for a number of reasons that aren't important here—if you get Your Mac is already up to date, the installer won't download. If it does, great since you won't have to tie it up downloading from the Repair Partition. If not, back to Command r
 
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jmpage2

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Sep 14, 2007
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Nope. It's the first thing Apple will tell you to do if you call them. If you take it to the Genius Bar, they will do the same before anything else.
[doublepost=1561041297][/doublepost]If the App Store will let you download the complete Mojave installer, that works, too. Enter Mojave Install in the App Store and click on Get.

This doesn't always work for a number of reasons that aren't important here—if you get Your Mac is already up to date, the installer won't download. If it does, great since you won't have to tie it up downloading from the Repair Partition. If not, back to Command r
Interestingly I haven't seen this for about five days since rebooting the box.

If I remember correctly the problem will be gone for a while after a reboot then start showing up again. This makes me wonder if some process is getting stuck or if there is some corruption or memory leak issue going on.
 

mikehalloran

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Oct 14, 2018
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Interestingly I haven't seen this for about five days since rebooting the box.

If I remember correctly the problem will be gone for a while after a reboot then start showing up again. This makes me wonder if some process is getting stuck or if there is some corruption or memory leak issue going on.
Memory leaks are going on. Absolutely, 100% assured. Web sites, applications, plugins... you can figure out all the sources with the right tools but can you do anything about it? Often not except for one thing:

Reboot on a regular schedule. For me, when I had less than 32GB RAM, it was sometimes more than once a day. With 32G, my interval turned to 36–40 hours so a daily reboot was fine. Now that I have 128GB, I can push it to 5 days but not 6.

Now that it takes around 45 seconds to reboot, open the apps I use daily and log into the 120–150 sites I go to daily for my work, it's not a big deal. When I had an HDD in my 2010, rebooting and logging in took 20 minutes.
 

jmpage2

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Original poster
Sep 14, 2007
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Memory leaks are going on. Absolutely, 100% assured. Web sites, applications, plugins... you can figure out all the sources with the right tools but can you do anything about it? Often not except for one thing:

Reboot on a regular schedule. For me, when I had less than 32GB RAM, it was sometimes more than once a day. With 32G, my interval turned to 36–40 hours so a daily reboot was fine. Now that I have 128GB, I can push it to 5 days but not 6.

Now that it takes around 45 seconds to reboot, open the apps I use daily and log into the 120–150 sites I go to daily for my work, it's not a big deal. When I had an HDD in my 2010, rebooting and logging in took 20 minutes.
Disappointing if true and a recent development. I have gone weeks if not months between reboots of any of my macs going back 10 years.
 

mikehalloran

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Disappointing if true and a recent development. I have gone weeks if not months between reboots of any of my macs going back 10 years.
So what?

This is not a recent development. Everybody chases memory leaks all the time including (especially) Microsoft and Apple. It wasn't new when I was doing it 23 years ago, either. Sometimes it affects users; other times it doesn't.

Web sites and browsers are among the worst offenders but it can be anything.
 

SaSaSushi

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Aug 8, 2007
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Disappointing if true and a recent development. I have gone weeks if not months between reboots of any of my macs going back 10 years.
I, too, go weeks between reboots and to date have had zero issues with memory leaks nor have I ever had any in over 13 years of Mac ownership. I have 40GB currently installed on my 2017 iMac.
 

mikehalloran

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Oct 14, 2018
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I, too, go weeks between reboots and to date have had zero issues with memory leaks nor have I ever had any in over 13 years of Mac ownership. I have 40GB currently installed on my 2017 iMac.
Actually, that’s not true and no amount of doubling down posts change that. But if you haven’t noticed, then good for you.

2017 was a particularly bad year for Apple in that regards.
https://www.macworld.com/article/3203966/slow-mac-could-be-a-hidden-memory-gobbler-in-macos.html
 

SaSaSushi

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Aug 8, 2007
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Takamatsu, Japan
Actually, that’s not true and no amount of doubling down posts change that. But if you haven’t noticed, then good for you.

2017 was a particularly bad year for Apple in that regards.
https://www.macworld.com/article/3203966/slow-mac-could-be-a-hidden-memory-gobbler-in-macos.html
Fair enough. IF memory leaks actually occurred (and I run a s***load of open apps and web browsers with dozens of open tabs) they were so minor as to not noticeably affect performance in any way whatsoever.

I certainly don't have a need to reboot the machine on a regular basis to maintain performance.​
 
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