Busting 7 myths (lies) about Mojave

Maybe we have just moved into an age of disinformation, but I keep seeing statements about macOS 10.14 Mojave which are plain wrong. Here are corrections to seven which you may come across. When you discover others asserting otherwise, please point them in this direction so that they can become better-informed.

And if you think that I have made any mistakes, please don’t hesitate to correct me!

1. Mojave runs 32-bit apps just fine

Prior to WWDC 2018 in early June, it looked as if Apple was going to pull the plug on 32-bit apps in Mojave. However, it was stated very clearly at WWDC that Mojave is the last major macOS release which will run 32-bit apps “without compromise”. In case anyone is wrestling with the semantics of that, it means that Mojave runs 32-bit apps just fine.


What does happen in Mojave is that the first time that you run a newly-downloaded 32-bit app (with its quarantine flag set), you will see a warning dialog. Read it carefully though, as it is not telling you that Mojave can’t or won’t run that app, just that you need to be looking for an update/upgrade/replacement, otherwise later in 2019, when macOS 10.15 ships, you may have to run that app in a special 32-bit compatibility mode, or whatever solution Apple arrives at.

There is, actually, a significant sub-text here too: if an app is still only available in 32-bit mode, it’s likely to be old and graunchy and may well have other problems. I have had to give up using Mailsmith, my favourite email client, because it is struggling with Mojave in other respects. Its last version was built in May 2018, but it looks like it is finally on its last legs.

2. APFS in Mojave works fine on all regular storage media

When Apple released High Sierra just over a year ago, it pulled support for its new file system, APFS, on hard disks and Fusion Drives at the last minute. Again, at WWDC 2018 back in June, Apple made it clear that Mojave’s improved APFS would support hard disks (that had already been introduced in High Sierra) and Fusion Drives.

When you install Mojave onto an SSD, hard disk, or Fusion Drive, if that is still in Apple Extended (HFS+) format, the installer will try to convert that storage to use APFS. There is no option for it to do otherwise. This is now the third major release of APFS: the first was in Sierra, and the second in High Sierra. Although its performance on hard disks may not be stunningly fast, APFS is now the standard file system for macOS.

When a Fusion Drive is converted from HFS+ to APFS, it involves quite a radical change. In HFS+, Fusion Drives are ‘glued together’ using another layer of software, CoreStorage, which makes the two disks look as if they are one.

APFS doesn’t use CoreStorage, but according to Apple’s latest documentation the SSD component in the Fusion Drive is used as a cache for its companion hard disk. For the purposes of reading files, the SSD and HD contain the same file data (Apple doesn’t explain which of the files on the HD are so cached on the SSD, though). For writing files, the Mac writes to the SSD and space is allocated on the HD to receive that data in slower time.

In Mojave, APFS is not used as the default format for optical media (which still use their traditional formats), volumes which are used to store Time Machine backups (see below), and networked storage such as NAS. USB ‘thumb’ drives or ‘memory sticks’ can be formatted in APFS, or you can use conventional PC formats such as ExFAT for interoperability.

3. Most apps don’t need to be updated/upgraded for compatibility

If an app already runs well in High Sierra, it is likely to run just fine in Mojave. Apple has made provision for this in most of the changes in Mojave, including its privacy protection.

Where you are most likely to encounter problems is with Mojave’s Dark Mode, as only recent versions of Apple’s Xcode development system have provided full support for that. If you only run in Light Mode, the great majority of High Sierra apps should work fine.

When you switch to Dark Mode, older versions of some apps can be almost unusable, though: their text may display in black on Dark Mode’s very dark backgrounds. In most cases, there is nothing that you can do other than update to a version which has been built to work properly in Dark Mode, and that is what most recent software updates have been concentrating on.

4. There are relatively few problems upgrading to Mojave

With millions of users upgrading to Mojave, it is inevitable that some run into problems. So far, they seem quite uncommon, and most likely if you are upgrading an encrypted startup volume (FileVault), particularly if it’s also a Fusion Drive. If you are coming to Mojave from Sierra or earlier, that may be a big leap for your Mac, and sometimes it is easier to take it in stages, upgrading first to High Sierra and from there to Mojave.

If you prepare well for the upgrade, and ensure that you have at least one full backup from which you can restore all your files, the worst that is likely to happen is that you’ll have to erase your startup volume and install Mojave afresh. The potential exceptions to this are models with T2 chips (iMac Pro and MacBook Pro 2018): because of their Secure Boot process and default encryption, they can prove more difficult. If you have problems with a T2-equipped Mac, contact Apple Support as soon as possible as they now have experience and knowledge of helping users through this process.

5. Time Machine still doesn’t work with APFS backup volumes

Time Machine hasn’t changed significantly in Mojave: it still relies on directory hard links in its backups. Those are not supported by APFS, so Mojave can only make Time Machine backups to HFS+ format volumes.

Before Time Machine backups can be stored on APFS volumes, Apple is going to have to change how those backups work, which will require Time Machine 2. This might come during the lifetime of Mojave, but I suspect that the earliest that we’ll see it is in macOS 10.15 next year.

6. Mojave’s privacy protection is good and valuable

Given how much has changed, the new privacy protection system in Mojave – TCC – actually works very well. Yes, there are now two known vulnerabilities in it which can be used to bypass some of its protection, but there is no evidence that either has been exploited in the wild.

What can’t now happen in Mojave is that an App Store app, or one which has been notarized for Mojave, sneaks behind your back and starts sending your private data back to someone else’s servers on the other side of the world. If such a malevolent app did somehow cheat itself through the code review processes of the App Store or notarization, Apple now has no option but to pull the app and block its developer immediately.

This doesn’t guarantee that other apps – neither App Store nor notarized – might try to exploit vulnerabilities in TCC, but if they’re going to be malware, there is more to worry about than mere privacy protection.

The robustness and effectiveness of Mojave’s privacy protection should continue to improve in the coming months. That in High Sierra and Sierra isn’t going to improve. Ever.

7. Mojave doesn’t necessarily bring lots of annoying privacy dialogs

Most Mac users don’t use apps which go anywhere near the data and services which are protected by TCC, so are very unlikely ever to see any of its consent dialogs. If you use automation apps which control other apps, though, when you first use them in Mojave, you may be assailed by a succession of consent dialogs. Provided that you agree to that app being added to the specific lists in the Privacy tab, you will not be prompted to agree to the same control pairing again, but will still need to consent to each app pairing, one at a time.

So for some users, you may see quite a lot at first. But once your privacy settings have settled, you probably won’t see them ever again. There is also the likelihood that improvements to this will be made in future updates to Mojave.