Mac users who have upgraded their SSD-equipped Macs to High Sierra are reporting compatibility problems with some widely used professional apps and some games.

While APFS is not currently supported on Fusion Drives, built-in flash drives in current Mac hardware are automatically converted to APFS from the old HFS+ file system when High Sierra is installed. Macs have been using HFS+ for 20 years, so the move to APFS is a monumental change. APFS has been in beta testing on Macs for months, and Apple gave it a public debut in iOS 10.3 in March, so it has already had some time out in the wild. The transition has been generally painless for a lot of users. But professionals should be careful about upgrading to a new OS while we wait for app developers to update their software and for a first major update to High Sierra from Apple.

In one example of compatibility problems, users have run into issues with Adobe Illustrator CC 2017 running on High Sierra Macs with APFS drives. Adobe has acknowledged the problems to its users, saying, "there is no workaround" but that a solution will come in a future update. New installations of Illustrator may fail, and running a previously installed copy on an APFS drive can lead to all sorts of problems when launching the application or opening files. There is also a more minor problem with color settings, but there is a workaround for that one.

Additionally, Unity , one of the most popular software suites for Mac and iOS game development, has had some issues on APFS drives . The same goes for the game Cities: Skylines , which was made with Unity. While some of the problems (like disappearing assets) have been fixed with updates to the Unity Editor, Unity still recommends holding off on updating to High Sierra, as there are still a few issues to be ironed out whether they are related to the file system or not. For example, Unity's default IDE MonoDevelop crashes in High Sierra when its window is dragged between two monitors. AppleInsider additionally reports that gamers have complained that games running Valve's Source engine and Steam also encountered minor bugs and performance reductions right after launch.

A surprising security vulnerability related to password-protected drives was also discovered and attributed to APFS, but it turned out to be a Disk Utility problem and was hotfixed by Apple today. A software developer named Matheus Mariano created a Medium post describing the vulnerability when he found it. He created an encrypted APFS container and password protected it, then entered a password hint as recommended. He then unmounted the drive. When he mounted it again and was prompted for a password, the displayed password hint was actually the plain text of his password. MacRumors duplicated the issue and clarified that it's a bug with the Disk Utility application, because the password hint displayed correctly on a drive instead created through Terminal.

Apple just released a supplemental update today for High Sierra in the Mac App Store. It fixes this vulnerability and a couple of other minor bugs with Yahoo mail accounts and Adobe InDesign. But for most pro users, the APFS application compatibility problems are the more immediate concerns.

These are all the sorts of problems that are usually ironed out expediently with software updates either to the applications or the OS; there's no doomsaying here. It just means you should continue to be careful about updating to High Sierra if you or your organization depend on professional applications.

Correction: A previous version of this story said iOS 10.3 launched in July, but it launched in March.