We’re now past Catalina’s midpoint: with four versions already released, there’s only three more to go before we prepare for the first release of 10.16. That’s a stark fact, that we’re now at the point where the more cautious should consider whether they’ll run 10.15.

Unusually for macOS, there are many Mac users with Catalina-compatible Macs who are no more able to upgrade now than they were back in October. These include the many who still have to rely on 32-bit apps, and those whose Mac doesn’t start up from an SSD.

If you’re still reliant on 32-bit apps, then this could disqualify upgrading before you’ve even looked any deeper. Perhaps the most common examples are those still dependent on Adobe CS6 or earlier. There’s no like-for-like upgrade which they can purchase – all options from Adobe require a costly subscription to CC, which is a non-starter for many of those who rely on CS6 apps for hobbies or low-paid work. There are worthy replacements from Serif, but there remains the problem of maintaining access to all your old documents.

There are other orphaned apps which don’t have direct replacements which run on Catalina, such as those working with Contacts to support extended features such as custom layout printing. Given the decline in printing, it looks unlikely that there’s sufficient demand to make replacements commercially viable.

Anyone reliant on HFS+ features also has a problem, as there’s no option in Catalina to boot from anything other than an APFS Volume Group. Ironically, this is the catch with Time Machine at present, which still requires users to keep their local backups on an HFS+ volume.

One substantial group of users here are those whose Macs boot from a hard disk, or even a Fusion Drive. As Apple continues to sell several iMac base systems with internal hard disks, this group isn’t going away in a hurry. APFS performance on hard drives is not good, and there remain questions as to whether it’s a wise option for Fusion Drives, particularly those with smaller SSD components. In the case of hard disks, this isn’t something which Apple is likely to improve much, as it results from the design goals of APFS for use on SSDs.

Of those users who can upgrade, the question is whether it’s safe to do so yet. As far as macOS goes, there are relatively few serious issues which have become apparent.

The most important relate less to 10.15 itself than to its bundled apps, particularly Mail and its bugs which have lost messages, and Time Machine’s backups. Mail bugs haven’t been general, and 10.15.3 does at least fix one of the more serious bugs if reports are anything to go by. But Michael Tsai considers that at least one remains. As Apple doesn’t appear to have acknowledged any such issues, or mentioned the fix in 10.15.3, it’s not clear whether it can be relied on to address remaining problems. For heavy Mail users, this may still be a good reason to further delay upgrading.

Time Machine issues are equally frustrating because of Apple’s failure to communicate. There are small warnings in passing in various support notes that upgrading could result in changes to Time Machine backups, which makes them incompatible with previous versions of macOS. This wouldn’t be a problem, perhaps, if conversion was completely reliable, but a small and significant minority of those who upgrade to Catalina lose all their old backups, which is devastating, particularly when they’re completely unprepared. Simple solutions such as starting a new backup series or archiving your old backups aren’t as easy as they may sound.

The upshot is that there are going to be many Mac users who simply can’t risk upgrading to Catalina, and will be stuck running High Sierra, whose support is expected to end later this year, or Mojave, whose support should expire in just over 18 months. Apple needs to reconsider whether its current support policy is realistic if there’s a growing number of users of currently-sold Macs who are stuck running older versions of macOS in the future.

Plenty of users buying new Macs in 2019 and 2020 will find that support for their macOS expires long before their hardware does. The glib answer that their hardware is capable of 10.15 and 10.16 just won’t do if they’ve got an internal hard disk and a slew of apps which they can’t run on anything newer than macOS 10.14. One solution for many of those orphaned users could be an at-cost Apple programme to replace hard drives (and possibly Fusion Drives) with SSDs in recent models, so at least those models can boot and run Catalina briskly from their internal storage.

For many users, the drawbacks in Catalina are largely the result of Apple becoming over-extended: Catalina runs best on Macs with hardware specifications that Apple marketing isn’t yet prepared to make the baseline for models such as the iMac. This all seems horribly like the mess that Apple got into over the amount of memory supplied in the original Macs during the first year of their release, when everyone knew that 128 KB of memory was insufficient, but Apple still soldered that into its base model of Mac.