I’ve been running OCLP (the Open Core Legacy Patcher) on my 2012 MacBook Pro; recently I ran softwareupdate from the command line and accidentally upgraded to Sonoma from Ventura. The experience was definitely mixed.

It handled it mostly okay for day-to-day work. Xcode 15.4 ran fine. Where I hit a problem, though, was when I tried running Azuracast under Docker. The machine ran insanely hot, so hot that it started throwing screen glitches. Rather than burn out my GPU, I elected to downgrade to Ventura. Here’s how that went. (Spoiler: a lot of toil.)

Getting Ventura back

The first step was to get Ventura back on the machine, This wasn’t particularly hard; I just needed to follow the standard OCLP procedure, but install to a new partition on my internal SSD. This cut the amount of space down by about another 200GB, but went well. I was able to install and have Ventura in good shape in a couple hours.

Retrieving the data from Sonoma

Here’s where we started having problems.

I had hoped that I’d be able to use Migration Assistant to bring the data back from Sonoma to Ventura, but no dice. Migration Assistant looked at the Sonoma disk, said, “nuh-uh, I ain’t downgrading” and refused to even consider mounting the disk. This meant I’d have to port everything back from that disk to the new one manually.

My first try was to rsync it over. This failed because now I didn’t have enough space to have two copies of the data. I deleted the data from the Ventura install and tried again. This time I created a service account with admin privileges, and copied ~/Library over from Sonoma. This didn’t seem to work either; most particularly iCloud login was broken.

Fixing the broken copy

After thinking about it a while, I decided that the problem was probably permissions. From the service account, I wiped the Ventura copy of my account again, and copied in two steps. First, I copied ~/Library over, then chown‘ed it to my user on the Ventura disk. I logged in as myself, set up iCloud, and all was good. Now came the question of moving the data without filling the disk.

I was able to use rsync (from the service account again), but this time I added --remove-source-files and --ignore-existing to the command. This copied only files I didn’t already have on Ventura from Sonoma, deleting them as they transferred. After this finished, I logged in to my Ventura account, iCloud was okay, and all my files were back.

I then rebooted into the installer again, removed the Sonoma partitions, and was ready to go.

I’m now currently running Azuracast under Docker, and having it ingest the RadioSpiral tracks from my iTunes library. It’s running warm, but not hot, and no more screen glitching. I’ll probably leave it on Ventura unless someone else running the same machine gets good performance from Sequoia.

And I can always run Linux if all else fails.