Classic Mac Pro owners; stick with Big Sur or downgrade?

The Classic Mac Pro (cMP) has been stuck on Big Sur version 11.2.3 for a bit now. There have been many fine folks working on a solution but, at least for now, 11.2.3 appears to be the end of the line for us. So the question is; stick with this early version of Big Sur, or downgrade to an older OS?

In this post I’ll share my train of thought on the matter.

Spoiler alert; This will not be a list of pros and cons, you will have your reasons for wanting to stick with Big Sur at all costs. This will be me making the case for a downgrade.

Yes, Big Sur offers features and functionality the older OS’ don’t have. And in the long run you may enjoy compatibility for apps that set Big Sur as their minimum OS version. But you won’t be able to deal with the two biggest issues Big Sur 11.2.3 has.


Big Sur 11.2.3 is an immature OS, there are still tons of bugs to be worked out. Since 11.2.3 there have been three updates (at the time of writing). These updates had a ton of bug fixes in them that cMP owners are currently missing out on.


With every OS update come security patches as well. As with the bug fixes, cMP owners are missing out on these security updates as well.

But Jay, a newer OS is always more secure than an older OS. In this case, it is not. Every time Big Sur receives an update, Catalina and Mojave receive security updates as well. While cMP owners are stuck on Big Sur 11.2.3, Catalina and Mojave users are still receiving their security updates. Making Big Sur 11.2.3 much less secure than it’s older counterparts. Apple is nice enough to publish a list of exactly which security vulnerabilities it has found and patched. These list are super handy for malware creators, hackers etc. to know exactly which vulnerabilities to exploit in unpatched and older systems.

let’s take one of the most recent security patches Big Sur 11.4 received:

Available for: macOS Big Sur
Impact: A malicious application may be able to send unauthorized Apple events to Finder
Description: A validation issue was addressed with improved logic.
CVE-2021-30671: Ryan Bell (@iRyanBell)

This vulnerability was being actively exploited by the XCSSET malware. Big Sur got the patch but cMP owners can’t install it. Catalina got the patch in the “Security Update 2021-003 Catalina” update, making this an already more secure version of macOS. Mojave was not affected in this case as it does not use that framework. This is just one of hundreds of examples where Mojave and Catalina users are being protected with updates and cMP owners are being left behind.

An older OS version which has been fully developed and discontinued, is different than an OS version that is still in early development stages and stuck there. The updates for Big Sur will keep on coming and with it, the list of vulnerabilities published by Apple. An ever expanding road map on how to exploit Big Sur 11.2.3. Catalina and Mojave won’t face this problem, when their support ends, no more updates means no more vulnerability lists from Apple. Sure, vulnerabilities will exist and surely they will be discovered at some point, but finding them will be a tad bit harder. Meanwhile, those stuck on Big Sur 11.2.3 will always find themselves OS version that’s in early development stages with tons of documented vulnerabilities.

A good firewall and anti malware software can help but fighting the slew of documented vulnerabilities and making sure your 3rd party software protects you from it will become a full time job.

My two cents: Downgrade to Catalina or Mojave. Mojave started out rough but has matured into a robust and reliable OS version before it was discontinued. Security updates are still released for it and the OS is new enough to enjoy compatibility with most current software. Catalina has it’s fans out there, I’m not one of them (I need my 32-bit software!), and of course that OS will enjoy security updates a year longer than Mojave.
Both of these OS’ run really good on our cMP’s with the help of OpenCore too.

Fingers crossed, some genius out there will figure out a way to make Big Sur 11.4 and newer work on our cMP’s. Maybe the new macOS 12 Monterey will offer the solution instead. But there is a good chance that Big Sur 11.2.3 is simply the end of the road for the cMP. At the moment, it is the end of the road. And until it isn’t, I suggest downgrading to Catalina or Mojave. If you don’t want to use an older version of macOS, at least explore a current version of Linux that’ll run on the cMP.

Let me hear your thoughts in the comments!

3 thoughts on “Classic Mac Pro owners; stick with Big Sur or downgrade?”

  1. I am in the camp that will more than likely downgrade to Mojave. The reason being is that I no longer run a GPU that requires Catalina or higher to run. Second Mojave is the last native version that will run on the cMP without patchers. Third because of this and because I am using an apple flashed GPU I no longer need open core as well. I can go back to running an OS on my cMP without any patchers or hacks.

  2. The mature os is always the best choice IME. Unless you’re an early adopter and have an absolute productivity-halting requirement for the newest, buggy iteration, running behind the herd of trust fund fueled fanboys on a polished, mature platform is ideal. The fact that there are multiple older os options that are still receiving security updates today only drives this home further. The mature os is clean, efficient and polished. Current software is still readily available for it. Using what one already has is both cost and time effective/efficient. It’s secure and maintained. If you have no absolute need (and I think most folks are in this camp) really it’s a no brainer.


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