My 2019 iMac i9 has developed a Sleep Wake failure in EFI Failure code after Big Sur install. I had no issues with sleep using Catalina, and everything has stayed the same as when I was running the previous OS. I just reset the SMC and Pram so we will see if that helps. Just woundering if anyone else has run into this issue.
iMac 27″, macOS 11.0
That finding could be pivotal. When I spoke with Apple support on the phone, the rep asked whether I had any peripherals connected to the iMac while it was sleeping, and asked to unplug them. The only thing that came to my mind was a UPS which connects via USB to let the computer know when it’s running on battery.
It was only later—after reading your post—that I realized something else: on many occasions, when the issue had occurred, I’d had an Apple Thunderbolt 3 cable connected to the iMac, and it’d been roughly around the time when I’d bought the cable back in October that I’d first started having the problem (i.e. before Big Sur).
The strange part is, the cable’s other end had usually been unplugged. Nevertheless, in the days since I’d disconnected both the UPS and the Thunderbolt cable, the iMac woke up just fine. I think it would take up to a couple more weeks of monitoring to really make sure it was the cable that caused the wake issue.
A hardware problem is likely. It could also be a bug in the OS itself, which isn’t a result of some software / configuration conflict.
I am on day 3 of running without a crash. When I first got the machine almost 2 years ago I also got a CalDigit TS3 thunderbolt hub. Since the problem only started a few months ago I did not think to unplug it. I did on Sunday and thing have been OK so far. I going to give it a few more days and them plug the dock back in and see what happens.
2019 iMac i9 Sleep Wake failure in EFI Failure code after Big Sur install
