Apple issues supplemental update for macOS Mojave 10.14.5 fixing T2 issues in MacBook Pro

in macOS edited June 2020
Apple has issued a supplemental update for macOS Mojave 10.14.5 for users of the 15-inch MacBook Pro, a recommended download that fixes a problem associated with the built-in T2 Security Chip.

Posted to its support pages on Wednesday, the macOS Mojave 10.14.5 Supplemental Update for MacBook Pro is described as addressing a "firmware issue" that specifically affects versions of the 15-inch MacBook Pro equipped with the T2 Security Chip. This effectively covers all MacBook Pro models introduced since 2018.

The size of the supplemental update is 952.9 megabytes, and is downloadable from the support page directly rather than as a standard system update. Information about the actual contents of the update is unavailable at this time, as the Apple security updates page has yet to be updated.

It is unclear what exact issue the update fixes, but the T2 chip has been blamed for a number of problems since its introduction. The T2 chip has been found to block some third-party Mac repairs from being performed, may have caused errors for some MacBook Pro users installing macOS Mojave, kernel panics, and is also reportedly interfering with some professional audio interfaces.

The T2 chip handles a number of functions on behalf of the rest of macOS, including boot and security functions, faster disk encryption to the onboard flash storage, regulating fan speeds, managing the speakers, securing the built-in microphones, managing the image quality of the FaceTime camera, and powers the "Hey Siri" vocal prompts for Apple's digital assistant.


  • Reply 1 of 12
    emoelleremoeller Posts: 527member
    It was 1.27Gb and I installed it via Settings/Software Update.   I didn't have any issue that I was aware of before on my 2018 MBP and couldn't see any difference after the install.
  • Reply 2 of 12
    macxpressmacxpress Posts: 5,172member
    Sometimes issues you'll never see even though there is an issue. Its all on the backend sometimes. 
  • Reply 3 of 12
    cgWerkscgWerks Posts: 2,720member
    Hmm... since 10.14.5 my 2018 Mac mini has frozen up 4 times now (or maybe 5, I'm starting to lose count... it just happened a couple of hours ago, again).
    It only issued a crash-log once, which I sent to Apple. The other times I just had to hold the power button, and it booted back up w/o a message (or seemingly any data-loss).
    I wonder if such an issue with the T2 is broader than the MBP, but they just haven't gotten to it yet?
    edited May 2019
  • Reply 4 of 12
    pczarpczar Posts: 1unconfirmed, member
    Since update to 10.14.5 my iMac frozen few times on login - never ever before. After long hold power button re-logged each time without visible problem. Something is not right there.
  • Reply 5 of 12
    cgWerkscgWerks Posts: 2,720member
    pczar said:
    Since update to 10.14.5 my iMac frozen few times on login - never ever before. After long hold power button re-logged each time without visible problem. Something is not right there.
    Yeah, all but one (which was pre-10.14.5) has been in the lock screen, so I can't really tell what is going on. A couple of times, from the heat, it seems it was still doing stuff, and the logs show general activity. So, it isn't 100% frozen... though the clock stops, etc. at least on the screen-saver. Fortunately, same as you, no visible issue resulting from the hard-power cycles. Maybe that's due to the newer file system? But, it makes me really, really nervous!
  • Reply 6 of 12
    inequalsinequals Posts: 17member
    wow, so I've been troubleshooting a T2/TouchBar issue causing panic reboots ever since I got my Mac. Enlisted the help of AppleCare if only so that it's documented if it turns out to need a hardware repair. I think that it only happens when I'm running BetterTouchTool with one of the crazy complex user made Touch Bar preset available for it. But I can't be sure. I'm definitely running that now I've installed the Supplemental Update and hoping against hope that the issue(s) they fixed are the ones I was seeing symptoms of. Because a Touch Bar without BetterTouchTool is ... undercooked chicken :D
  • Reply 7 of 12
    cgWerkscgWerks Posts: 2,720member
    It's so hard to tell with all the variables... but just to add to the thread:
    I had been running the 'Brooklyn' screen saver (the one with all the cool Apple logos morphing), but since my lockups had been in the lock screen, I went back to the simple 'Message' one. Knock on wood, but no lockups since.

    But, again, I haven't necessarily been running the same stuff for extended periods since that change, so just a precaution. I might switch back in a couple days again just to see if I get more lockups.
  • Reply 8 of 12
    gkhangkhan Posts: 1unconfirmed, member
    It killed my imac late 2015! My imac frozen few times and i came back to 10.14.4
  • Reply 9 of 12
    Mike WuertheleMike Wuerthele Posts: 6,257administrator
    gkhan said:
    It killed my imac late 2015! My imac frozen few times and i came back to 10.14.4
    This particular patch has nothing to do with your 2015.
  • Reply 10 of 12
    duncanrmiduncanrmi Posts: 1unconfirmed, member
    got mojave 10.14.5 on my 2013 mbp 15" retina, & it's shit. fans running fast, half the apps don't honour my preferred 'light' theme (i.e. as it was before mojave), with QT player in particular always opening finder windows in the dark theme. this latter app won't close without prompting for a save when I've already saved a trimmed clip. I dunno, apple... every update seems to make the machines more difficult to use these days. are you microsoft in disguise? :-/
  • Reply 11 of 12
    bytor2112bytor2112 Posts: 1unconfirmed, member
    my 2014 mac mini crashed would not install 10.14.5 I tried multiple times got tired of having to revert back to 10.14.4 bt I am still having problems I didn't before so no update for me
  • Reply 12 of 12
    With the lasted update, I've experienced on going flickering folder names and locked up screen. Annoying!
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