Repeat with any other backed-up data not stored in Time Machine (e.g., Dropbox, Box, Google Drive, etc.) Use the Migration Assistant to restore your files from the Time Machine (or whatever) backup back to the Mac. Remember, everything's running off the external drive with the OEM SSD. Run the installer, and use it to install High Sierra on the internal drive. Go to the Mac App Store and redownload the 'Install MacOS High Sierra' application. Use Disk Utility to erase and reformat the internal (OWC) drive. It will slow down a bit, but it will work. You will have the option to boot from the internal (OWC) SSD into the old MacOS version, or the external (OEM) SSD into High Sierra. Plug in the external, reboot, and hold down Option at the chime. Install the OEM SSD in the external enclosure, and the OWC SSD in the MacBook. Open up the Macbook again and remove the SSD. You now have High Sierra, but on the wrong drive, and none of your data. Reboot, and using an administrator account, install macOS High Sierra on the OEM SSD. It will be an old version in my case Yosemite. Use Disk Utility to erase and reformat the internal drive, and install a clean macOS on it. Open up the Macbook, and replace the OWC SSD with the OEM one.īoot into recovery mode (command-R at startup). Also, this process wipes both the original and the new (OWC) SSDs clean, so you need a recent backup, for instance Time Machine. The screwdrivers (P5 and T5) come in handy too. It's inspired by, but slightly different from, this process outlined by MacSales in How to Format a New Internal SSD in macOS High Sierra.įor this process, you need not just the original (OEM) Mac SSD, but also the enclosure that OWC sends with their upgrade kit. Here is my process with the non-functioning loops edited out. Then re-install the OWC drive, and upgrade that to High Sierra. Then upgrade to High Sierra, which will update the Mac's firmware. Update: I have spoken with OWC customer service, and they say I will need to reinstall the OEM SSD. Also, if the fault is in the drive itself I'm not sure it would work. But that takes so long I'd like to avoid it if I can. I have an external Time Machine drive with a recent backup, so I guess I could attempt reformatting the OWC drive, installing High Sierra, then restoring from Time Machine. Or, if it has to do with attempting a three-version leap in the OS.

I'm not sure if this is related to other posts ( e.g.) I've seen about OWC SSD drives installed internally but appearing as external. The installer won't run on this drive, complaining that that it's missing a firmware partition.

I am now trying to upgrade to High Sierra. Everything has worked fine up to now, although the OS still recognizes the SSD as an 'external' drive. Last year I replaced the Mac's internal 500GB SSD with a OWC Aura 1TB SSD. I have an early 2015 Macbook Pro running Mac OS Yosemite.

Owc aura pro x2 firmware update