Carbon Copy Cloner dev: Apple’s macOS 10.15.5 has a trivial bug or a ‘reprehensible’ decision

Apple’s macOS 10.15.5 either has a trivial filesystem bug or Apple has made a ‘reprehensible’ decision, says Carbon Copy Cloner developer Mike Bombich.

Mike Bombich for Bombich Software:

macOS Catalina
macOS Catalina
Early last week we discovered an APFS filesystem bug in a beta of macOS 10.15.5. The technical details of the bug are laid out below, but the short version is that we’re no longer able to use our own file copier to establish an initial bootable backup of a macOS Catalina System volume. To be very clear – existing backups are unaffected, and this has no effect on CCC’s ability to preserve your data, nor any effect on the integrity of the filesystems on your startup disk or your backup disk. The impact of this bug is limited to the initial creation of a bootable backup.

Could this simply be a security fix – maybe Apple doesn’t want third-parties to create firmlinks?

If that’s the case – if this is not actually a bug and is actually an intentional change by Apple, then I would argue that this is far worse than a bug. First, if third-parties should not set or remove the SF_FIRMLINK flag, then that should be documented alongside the flag’s definition (i.e. in /usr/include/sys/stat.h). Second, if you’re not going to allow the setting of the SF_FIRMLINK flag, then the system call should return -1 and set errno to EPERM – reporting success and failing is reprehensible. Last, and most important – making such a change in a production OS release with no warning is openly hostile to third-party developers who were relying on the documented functionality.

I suppose we’ll find out in future OS releases whether this was a simple filesystem bug that slipped into a production OS release, or if Apple finds it to be an acceptable practice to blindside developers by silently removing documented functionality in the middle of a production OS release cycle.

MacDailyNews Take: This sounds like a bug – the alternative doesn’t sound right – so we’re going to assume a bug fix is coming until we hear otherwise from Apple themselves.

[Attribution: 9to5Mac. Thanks to MacDailyNews Reader “Fred Mertz” for the heads up.]


  1. I have 3 macs. My newest iMac kept crashing after installation of MacOS 10.15.5, so I had to use TimeMachine to restore it to it 10.15.4. My older MacBook Pro and Mac mini have been okay.

  2. Even if the bug is apple missing to document this, that is another option. There are thousands upon thousands of changes, tweaks and updates to macOS, and missing documentation on one change – completely understandable.

  3. It’s a beta version correct?

    If so, don’t wet your pants.

    Oh silly me, I also thought a company like CCC would have both good developer relations and a direct contact inside Apple. Perhaps, “Not anymore”.

  4. There was once a time when you could just hit “Select All” in the finder, drag all the icons to a new HD, and have a bootable backup of all your files. It speaks badly of Apple that you need to go to a third party to do stuff like this. MacOS has deteriorated so much.

  5. Nope It’s all Apple’s fault. They are trying to lock down their system by any means. There’s no reason to use multi partitions for the OS, Why does the OS have to call home everytime you open an app for? It’s getting ridiculous and no one is creating a stink about it. Every year Apple is getting more and more Strict and finicky which they shouldn’t. It used to be a friendly OS for the users, Now it’s a platform to make money and snitch on you. We need Innovation and a revolution at Apple.

  6. According to CCC on their blog, they informed Apple of this bug prior to the release of the new version of macOS, so this was overlooked by Apple or worst case scenario, they didn’t care

  7. Totally agree.

    I just purchased a new MBP 16″ and the mail app doesn’t let you show the To, From, Subject, Date, column headers while viewing your inbox. Also, I had to use the terminal to get the startup chime back and to give me the ability to turn on the mac manually instead of it turning on automatically when you open the lid. Have been pondering returning it these last few days…

  8. Mike Bombich has been a solid ‘go to’ for the last 20yrs I have worked with Macs and is certainly someone who knows, from the ground up, the MacOS and, as a network engineer, more complex cross subnet NetBooting amongst many other delights. Apple would know this and if they don’t, they are far more stupid than I had thought over the last few years or…… they are making the change I suspect in that macOS will align to iPad/iOS…. A very closed env. This is not a good place for anyone as it stifles creativity and ability in the 3rd party sector. I am not going to get bogged down in the obvious security argument but I feel that, unless you are happy with a totalitarian regime, it is not something to aspire towards… Just my 2c

  9. I’ll always be an Apple cult member and have a few macs, but I’m seriously considering getting a sytems76 computer with Linux popOS for my next computer.

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