I have a late-2009 27" iMac. After upgrading to macOS Sierra, I've had it freeze approximately once or twice a day. The only way to get the system operational again is via a cold boot. When this happens, the mouse pointer still works but otherwise the system is unresponsive. I've never had this problem in 7 years using the same hardware, so at a bit of a loss.
iMac (27-inch Late 2009), OS X Mountain Lion (10.8.3)
So - after nearly three months of running Chrome, I "experimented" over the weekend and went back Safari. Two freezes in two days, after none whatsoever using Chrome for months. Also got beachball stall with iTunes and Photos working in background. Will be staying with Chrome indefinitely as I have no confidence at all with Safari on my machine. You're probably right - they're ignoring the problem at this point.
For me this is a Safari issue. I am running MacOS 10.12.3 with the latest version of Safari. I have now used Chrome for a while with no issues. Tried Safari again today, and the iMac again became totally unresponsive as described in earlier posts here. I have sent another bug report to Apple, and i hope many more users will do the same. This is a software issue, introduced with MacOS Sierra.
Sorry for the late response. Up until my post, I just saw the usual screen freeze of being able to move the cursor but not being able to click links or move windows. The latest was the spinning beach ball when I executed Photos or iTunes.
Similar problem with TWO iMac (late 2012) macOS 10.12.3 (16D32) Sierra booting from external Samsung Portable SSD T3 500 GB. Sometimes Desktop background becomes black showing items (files and folders). Really frustrating.
I have a similar problem with both my iMac and MacBook. The system stops responding to the mouse, then a few seconds later to the trackpad and keyboard. The only way to get it unstuck is to force a system restart.
fakeExpert, have you experienced this issue again? After downgrading to El Capitan, my machine has been stable, but as you mentioned that you've not had issues with 10.12.4 -- and with 10.12.5 having been released since -- I'm wondering if it's worth trying to upgrade again.
How much RAM do you have installed? You can check in menu > About this Mac. Sierra runs, but just barely, with 4 GB, but it really needs min. 8 GB to run properly.
You can also try running Safe Boot mode.
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Restart in Safe Boot mode by holding down the Shift key at startup. Safe Boot is quite slow because the OS performs some cleanup and verification tasks, so give it time. After you're completely logged in, restart normally.
I have 16 GB 1067 MHz DDR3. The good news is that the problem hasn't manifested at all today even though I did not yet get around to trying the Safe Boot suggestion you supplied.
I have been having this same problem, and noticed that it seems to happen while in Safari. Googling around, I found similar issue reported in El Capitan which seemed to be related to WebGL. Perhaps turning off WebGL in Safari will help? I am going to try it and see.
Update: Turning off WebGL in Safari did NOT help. It still froze up later in the day.. I think I will have to revert back to El Capitan. For the record, I have an iMac (27-inch, Late 2009) with 2.66GHz i5, and 12GB RAM.
I'm experiencing the exact same issue with an almost identical iMac.
My system is a 27-inch, late 2009 with a 2.8 Ghz Intel Core i7 with 12 GB 1067 Mhz DDR3 memory.
The hard drive has approximately 16% free space (157.05 GB of 999.35 GB).
I've booted into rescue mode and run disk utility -- the directory structure appears to be ok.
I'm not able to isolate the problem to a specific application -- to the point in the thread regarding Safari, it is running when this happens. Although it's almost always running.
I'm completely at a loss. System uptime for this machine has routinely been in the months, but I'm now forcing a re-boot at least a couple of times a day.
Since there appear to be at least 3 of us now with this issue on Late 2009 iMac's, I suggest we all report the bug to Apple. I will report it at: https://www.apple.com/feedback/macosx.html. If there are other avenues for formal bug reporting, please chime in. (PS. The frequent random freezes make my machine completely unusable, so I have been forced to revert to El Capitan. This means I will be unable to further debug this. But if anyone finds a reliable workaround, please be sure to post. Hopefully there will be a fix at some point from Apple.
I've submitted...will see what response comes.
How did you revert to El Capitan?
I restored my machine to the last TimeMachine backup made while running El Capitan. Took 15 hours. its a complete replacement recovery, so you will need to also manually save anything you may have worked on in Sierra.
Same issue here. iMac Late-2009 as well with 16Gb RAM. Tried many things but have not figured out a probable cause yet.
iMac freezes after upgrade to macOS Sierra
