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I'm on High Sierra, MacBook Pro, 2017. For some reason it wouldn't finish logging me in and turn the laptop off today's morning.

What I've tried so far: First aid says everything is OK, while giving error "ppm002" in diagnostics. I'm trying to upgrade to Mojave in hopes that it will fix it. While choosing a disk to install on and after typing the password - the disk disappears from the choice menu, and I can't proceed with installation.

Any ideas? I'd be glad if there is a way to save information from the ssd.

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  • Sounds like the disk is dying...
    – Steve Chambers
    Commented Mar 21, 2019 at 11:44
  • @SteveChambers from what I've heard it is a popular problem with mac models like mine. Had to send the laptop to Apple Support
    – vladli
    Commented Mar 22, 2019 at 14:20

2 Answers 2

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Error PPM002 points to a memory (RAM) issue. See Apple Diagnostics: Reference codes for more info.

Edit #1: I'll expand a bit - I had a 2014-era iMac in for repair early last year because it wouldn't update to High Sierra from a seemingly working Sierra, and in the end it turned out to be faulty memory. Whether this was due to a specific way that macOS accessed the RAM during an install, I don't know. What I do know is that it was faulty RAM and replacing it solved the problem. There was a PPM error, though I don't recall the exact number.

Your MacBook Pro (assuming Mid 2017 model) has soldered RAM, which means if it is faulty, then it's going to involve an Apple repair or replacement. Unfortunately it's not possible to just pop the RAM out and replace it.

Some things to try:

  • run Apple Hardware Test to do a full check of your RAM. Any Apple authorised technician will run this as part of their tests, so it's useful to get something concrete.

  • use another Mac to make a bootable High Sierra (not Mojave) USB stick, take a full backup of the drive using Disk Utility. The bootable installer (which doesn't actually require you install anything to the hard drive) is more lightweight on RAM use, so you have a good chance of getting your data backed up. If you're using Time Machine and it's up-to-date, disconnect that for now so you know you have a relatively safe backup if your MacBook does need to be repaired/replaced.

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  • Unfortunately that doesn't answer the question. That's like the first google search on "ppm002" error.
    – vladli
    Commented Mar 22, 2019 at 14:19
  • @ClaudH: I've expanded on my answer.
    – Pete Cooper
    Commented Mar 23, 2019 at 11:06
  • Thanks, @Pete. I've tried to get a backup - but after decrypting the drive it disappeared from the select menu :( After it comes back from repair I might have more insight as of what went wrong there.
    – vladli
    Commented Mar 28, 2019 at 8:47
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In case you don't want to repair the Hardware, there is a chance that only a fraction of your RAM is damaged.

In that case you could use a tool that I wrote which you run before every macOS boot (can be automated too) to mark this RAM-Area as unaccessible for macOS.

https://github.com/0nelight/macOS-Disable-RAM-Areas

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