MP 1,1-5,1 Mac Pro 5,1 > How To Reinstall Mojave

[5comma1]

Mid 2010 Mac Pro 5,1
Memory 48GB
Firmware 144.0.0.0.0
Sonnet M.2 4x4 PCIe NVMe card
OCLP 2.1.2
flashed RX 580 Pulse
two Dell 27” displays
Mojave 10.14.6
Monterey 12.6.3
Sonoma 14.7.1


Hello—

My inexperience bit me recently when I accidentally erased my Mojave disk (10.14.6)— which was my primary OS and the final OS available for the Mac Pro 5,1. I’ve reinstalled Mojave twice now and each time the process goes smoothly and everything appears normal, but subsequent attempts to boot Mojave after the initial setup result in the prohibitory symbol (circle with a slash through it). I’ve been attempting to install Mojave on one-half of a partitioned 2tb NVMe drive— which, as I understand it, should be fine. I’m also running Monterey and Sonoma via OCLP and both run fine. The Mojave version I’m working with is attached. Hoping someone can enlighten me around what I need to do differently. Many thanks in advance!

 

[Borowski]

Remove the drive with OC installed.

 

[5comma1]

Thanks for the suggestion, Borowski.
I'll give it a whirl. 👍

 

[MarkC426]

Also, once you have Mojave back up and running.
Use SuperDuper or Carbon Copy Cloner to clone it to another drive.

This can then be cloned back if you accidentally erase it (this was so much easier on intel Macs…)

 

[Borowski]

If you installed all OS on one single drive, you can boot Mojave:

• native via Apple bootpicker, press alt-key while firing the machine up and select your Mojave installation/installer
• or from OpenCore bootpicker, press esc-key while booting, but before you MUST insert the entry "-no_compat_check" in the config.plist to continue booting and avoid the prohibited-sign.

 

[5comma1]

Also, once you have Mojave back up and running.
Use SuperDuper or Carbon Copy Cloner to clone it to another drive.

This can then be cloned back if you accidentally erase it (this was so much easier on intel Macs…)

Thank you, MarkC426. Yes— I've been using SuperDuper for years to create bootable clones (Intel) and it's been great. As I understand it, creating bootable clones using OS's after Mojave became more difficult, or impossible. Is that your understanding?

 

[MarkC426]

I have just been on Shirt Pocket site, and the latest version (3.9) does say fully bootable clones up to Sequoia and AS native.

I did do a new clone of my Mac Studio at the weekend, and it shows up under startup disks (but haven’t tried it yet).
Info also shows both disks are the same volume size overall.

I am sure previously it only copied the data container (which would be smaller than the whole disk).

 

[5comma1]

Thanks for the tips, Borowski. I hope you or someone will have a moment to review my attachments. They might offer clues to getting Mojave installed correctly. I've had no experience with config.plist processes. Thanks!

 

[5comma1]

I have just been on Shirt Pocket site, and the latest version (3.9) does say fully bootable clones up to Sequoia and AS native.

I did do a new clone of my Mac Studio at the weekend, and it shows up under startup disks (but haven’t tried it yet).
Info also shows both disks are the same volume size overall.

I am sure previously it only copied the data container (which would be smaller than the whole disk).

That's REALLY good news!! Those bootable clones are the best! Thanks for letting me know! Yes, that's what I had heard... only data was copied in the interim when clones weren't an option.

 

[zapmymac]

Unplug as many drives as you can when doing this, makes it less confusing.

 

[5comma1]

Unplug as many drives as you can when doing this, makes it less confusing.

Thanks for the tip, zapmymac.

 

[zapmymac]

Thanks for the tip, zapmymac.

I’ve accidentally reformatted the wrong drive before. 🙃😵‍💫

 

[Borowski]

Thanks for the tips, Borowski. I hope you or someone will have a moment to review my attachments. They might offer clues to getting Mojave installed correctly. I've had no experience with config.plist processes. Thanks!

You're wrong, the Apple- and OC-bootscreen are changed.
Usually the Apple bootpicker has a grey background, but is changed persistent to black-white due to an NVRAM-entry (will remain until you delete NVRAM) by OC.

In your case to install Mojave: Press alt-key while booting, after every restart (until your Mojave is finally installed!) and select the "macOS installer" icon to continue/finish installation.

 

[5comma1]

I’ve accidentally reformatted the wrong drive before. 🙃😵‍💫

Thanks for being vulnerable (human) enough to admit it! 👍