I’ve got a mid-2011 iMac which sadly can’t be updated beyond High Sierra (grrr!). I tend to leave it on while I’m not using it, and usually (I mean on average every 24 hours or so), I come back to it to find a notice on the screen saying “Your computer was restarted because of a problem. Click Report to see more detailed info and send a report to Apple”. I usually do click ‘Report’ but as someone who doesn’t understand OS logs, I have absolutely no idea what happened to cause the machine to restart.
I nearly always use mainstream apps like Safari, Pages, Mail, Photos etc and they may be open when the crash comes, but there will be no user-initiated action going on. Of course there will be various timed actions like looking for emails, but then these are totally normal.
Frustrating. I would like to understand what kind of instability is occurring and why. I have no reason to suppose the hardware is in trouble, and the Internet connection is quite stable.
Has anyone any idea how common this is, and how to understand what’s going on?
My partner has a similar iMac (High Sierra is its max OS) and while hers doesn’t crash every night, it does do this overnight reboot at least once a week or so. If it happened every day I’d be more concerned, and would start by having the Console App running all the time, and then looking to see if anything weird happens around the time of the restart. Sometimes one gets lucky and the problem is obvious.
I, too, slogged along with over the hill iMac 24 (Early 2009) + MacBook Pro 17 (mid/late 2007) @ High Sierra… boy was that fun.
I, too, am somewhat tech-challenged, insofar as deriving benefit from the crash reports
I started using EtreCheck and have found it to be most useful in this regard. It scans your system and provides a most informative and useful ‘front end’ to the techno-geekery reports the system generates. It tells you what it found, what significance it has, makes suggestions, and has other tools to help you make decisions re how to proceed.
EtreCheck points out, their reports are commonly used in the Apple Support Communities when seeking help there
There’s a free and Pro version @ https://etrecheck.com, and the Mac App Store
p.s. Support is awesome
p.p.s Full disclosure - I’m in no way associated with EtreCheck other than being a well-satisfied customer
I can give you excellent advice towards troubleshooting the problem…but I actually need to know what problem you are having. It could be one of three things. It could be that your Mac is having Kernel Panics (a “crash”), it could be that your Mac experiences a hard shutdown due to power problems, or it could be that your Mac is simply restarting because some type of software is set to do this.
I’ve seen Macs restart spontaneously due to a sag in the power caused by something cycling on which is on the same electrical circuit, such as a refrigerator or a laser printer. In those cases a UPS with AVR always fixes the problem.
Assuming that what you are experiencing is a kernel panic, a Kernel Panic is a sign that you have a serious problem. It is likely that serious problem will worsen and lead to data loss if not attended to.
I’d say that about 80% to 90% of the time kernel panics are due to a hardware problem. In order of likelihood, that problem is usually:
bad third party RAM
a problematic USB hub
a peripheral that your Mac doesn’t like for some reason (sometimes just a poorly attached cable, or a bad cable, is the problem)
If you have very recently added new software, especially something that alters the system at a low level, such as anti-virus software, or something that changes the look and/or function of the Mac interface, I would suspect that first. Uninstall that software and see if things get better. (This type of software typically requires an uninstaller program from the product’s vendor to completely disable. Just dragging the application, or the application’s folder, to the Trash won’t disable it.)
If that isn’t it, I would restart your Mac with the Shift key held down (invoking a Safe Boot, with all kernel extensions disabled) and see if the problem is gone while running in Safe mode. If the problem is gone while in Safe mode, the Kernel Panics are probably due to a software problem. It it persists while in Safe mode, the problem is most likely hardware related.
To test for hard ware problems, you can run Apple’s Hardware Test/Apple Diagnostics:
Unfortunately, there is the possibility that you may have a hardware problem that this utility doesn’t identify.
If you suspect a hardware problem, the next thing that I would do is to shut down your Mac, uninstall all peripherals other than the Apple-supplied keyboard and mouse, restart and see if that helps. If it does, you can re-attach one peripheral at a time, restarting each time, until you isolate the offending peripheral.
If that isn’t a solution, I would remove all third-party RAM and see if that fixes things.
Thanks - I will take a look at EtreCheck. Murphy’s Law (inverse version) has kicked in and I haven’t had a crash for a few days now! Nothing has changed in my setup, apart from a security upgrade to the OS (now 10.13.6). However, I can’t really believe peace has broken out…
Randy, thank so much - that is all good stuff. It needs study, which will take me some time. Since I am not hugely inconvenienced by these crashes, which have been going on for months or even years at relatively infrequent intervals, I am unlikely to go down the more extreme paths, especially in the context of thinking seriously about replacing the machine with one of the newest generation.
Just in passing, I would say I do think it’s kernel panic.
I do have a very effective UPS, since historically the power supplies here in La France Profonde have been unreliable, although things have improved greatly recently. I seldom lose significant data during these crashes, as more often than not they occur when I’m not actually working, and I have a good backup regime, and I tend to save stuff a lot. But I’m still going to try to find out some more. Thanks again.
Yes, I have a Toshibea 1TB USB drive used for Time Machine attached to the iMac. It’s always on, and hasn’t been moved for over a year. I will of course check the connections. I am not at all sure I’m in control of its sleep pattern.
I do have a very effective UPS, since historically the power supplies here in La >> France Profonde have been unreliable…
How old is it? If it is more than three years old you might want to test it. Just about every time I’ve been to a client’s office and they’ve proudly told me that they use a UPS, I’ve checked it and the batteries have been dead.
Also, does your UPS have automatic voltage regulation (AVR)? I’ve tried UPS’s to deal with a power sag situation, and UPS’s without AVR don’t help the problem.