So I had this old, early 2009 Mac Pro (single processor variety) and I beefed it up with RAM (32-gig) and an SSD drive. I decided to test every MacOS operating system that was not supported by this machine using the OpenCore Legacy patching tool. In one case (Mojave) I used a similar patch from a fellow who goes by the name “dosdude1” on YouTube and elsewhere. By the way, the last officially supported version of OSX for this was machine was El Capitan. So, I tested the following:

• Sierra (worked with OpenCore patcher)
• High Sierra (worked with OpenCore patcher with a hiccup – throws an error when it attempts to verify, but, works fine)
• Mojave (failed with OpenCore patcher but worked with dosdude1’s patcher – internet had to be disconnected and date set to 2018)
• Catalina (failed with OpenCore patcher but worked with dosdude1’s patcher)
• Big Sur (worked with OpenCore patcher)
• Monterey (worked with OpenCore patcher)
• Ventura (worked with OpenCore patcher after I bought a decent quality USB thumb drive…..after numerous previous failures!)

The installations that went smoothly need no explanation. I watched a couple of YouTube videos, patched the installers, the patched versions were written to external USB devices and everything went smoothly.

The Problematic Installs

About High Sierra: When I ran the OpenCore Legacy patching tool on High Sierra it would write to my USB for quite awhile – writing about 5-gig – and then would stop with an error message that thing had failed. This was driving me nuts and I run the thing eight or ten times with different USB devices. I finally noticed that while the program displayed the message, “ERROR – Failed to create macOS installer” there was also some text at the bottom of the thing that said, “Patcher (501:6200) Done.” Here’s a screenshot:

I decided to just reboot the computer and see what happened if I tried to install from the failed USB installer – I thought maybe I would, somehow, get a clue as to what was happening. After all, the thing said it failed but it also said that the patcher was “done” – whatever the hell that meant. Anyway, the USB which had supposedly failed to be properly created worked just fine to install High Sierra. For reasons that only a smarter person could ever figure out apparently what was failing was the following: When you run the OpenCore patcher it writes for awhile and, then, validates what it’s written. Apparently the darned thing was writing fine, but, when it reached to validation portion the thing had a problem. Was the drive suddenly locked….had Jupiter aligned with Mars? I have no freaking idea.

Again, for whatever reason it was failing when it hit the validation phase but it was apparently being written completely and with no errors.

About Mojave:. As noted above this would not work with the open core legacy patcher but worked with dosdude1’s tool with the following caveats:

• The date, during the install, must be set to 2018 (I used ‘date 010109452018’ – I actually recall the exact date), and
• You must disconnect from the Internet during the install routine. Why? I have no idea.