Warning: Mac users, don’t convert your Time Machine volume from HFS+ to APFS

“Months after the release of macOS 10.13 High Sierra, folks are still having problems with limitations of the new Apple File System (APFS) format required for SSDs that run High Sierra, and which you can optionally upgrade other drives to use,” Glenn Fleishman writes for Macworld.

“You can use Disk Utility to upgrade a Time Machine HFS+ volume to APFS without a warning. You’d think Disk Utility would detect the Time Machine backup and stop you, but it doesn’t,” Fleishman writes. “Once upgraded to APFS, the Time Machine backup archive is mostly useless, even though files aren’t destroyed.”

Fleishman writes, “The archive becomes useless, because APFS doesn’t support hard links.”

Read more in the full article – recommendedhere.

MacDailyNews Take: Obviously, Disk Utility should warn users about upgrading a Time Machine HFS+ volume to APFS.


  1. This right here. No excuse for this bug getting past internal testing.

    I guess they had to pull the five guys from APFS development and assign them to the iOS battery issue. /s

  2. APFS is a hot mess. You still cannot use any commercial third party SW to recover and rebuild drives fully.

    DiskWarrior is still out to lunch and DriveGenius is incomplete last I looked. If your drive is FUBAR, good luck.

    This picture from Sarasota, Florida pretty much sums APFS up:

    1. Disk Warrior is merely waiting for Apple to resolve Apple’s own problems. Disk Warrior can’t be expected to develop appropriate software when the present situation is as muddled, unclear, and unstable as it is. Apple first needs to get its act together. So, Timmy, go to work – earn your salary.

  3. Time Machine. Cool concept, but another ‘hobby’ as while it works good initially, it never deletes old backups and the disk always gets full eventually, the only way to cure this is to re format the drive and start fresh. Which is counter intuitive for backups.

    1. As the disk fills up, it automatically deletes the oldest backups (of which the newer ones contain that data).

      Of course, the drive itself could get full if you have more (original) data than the drive’s capacity, but that is a different issue.

      Time Machine is a great system. However, anyone that uses it as their *only* backup is fooling themselves (APFS issues aside).

        1. I use both CCC and TM on several Macs for different purposes.

          You may have been experiencing a bug with TM, such that it wasn’t performing as it should, but it’s also possible another issue came up which is the result of one of the differences between TM and CCC.

          On TM, data must be copied, before old data is removed. IOW once the initial archive is performed, the disk will always maintain copies of all files.

          The problem that this poses won’t effect everyone, but here’s a great example:

          Suppose you have a 1TB system drive and a 1TB TM drive. You connect the TM and it creates an archive. If the system drive is almost full, say 950GB, the archive will be roughly 950GB initially (almost full as well). Under normal use, it will allow almost 50GB of archiving (past versions of files), and it will delete those files to make room for new versions.

          However, remember that it needs to maintain a copy of all files first. So lets say you go into a directory on your system volume like “Media” which contains all of your pictures, music and videos, and you change the name of that folder to “Multimedia”. TM sees that as a whole new set of data. If that data is greater than 50GB, it won’t be able to complete its session and will throw up an error resulting in the need to reformat the drive.

          You can change the numbers, or change the specific cause, but this issue can be a pain in the ass when you have either large data changes between sessions, or major structural changes.

          CCC runs into this same problem. The difference is that CCC has advanced settings that allow you to do things like “run a deletion pass” first.

          TL;DR: I highly recommend CCC for users with advanced needs, but TM does work well for most people with simple needs and is a lot easier for those less tech savvy.

          1. “You may have been experiencing a bug with TM…”

            Well, I’ve run into that very same ‘bug’ on several occasions too.

            Pragmatically, the only two realistic choices seem to be:

            a) Wipe the backup disk & start a new TM backup from scratch.


            b) Remove the offending drive, go buy a new (4TB or whatever) HDD and us it to start a new TM backup from scratch.


            FWIW, the other thing that TM does very poorly on is to be able to tell it, “hey, this drive went bad, so here’s its cloned replacement”.

            1. I’m not sure what you’re referring to by “that” but. I pointed out that the OP may have had any number of bugs, but other than that, there’s an issue with all archival software that may be what the OP is experiencing.

              Bugs aside, all archival software mah have an issue when high level structural changes to the data occur depending on the level of the change and amount of free space. CCC has the exact same problem that TM has.

              It’s not a bug.

              Yes, options A or B resolve the issue. CCC provides the same options as well as an advanced option of doing a deletion pass first. However, given the consumer nature of Time Machine, it’s understandable why Apple doesn’t provide this option, nor does it do a deletion pass by default. Doing that would mean wiping out data in advance of having data exist in two places at all times.

              It’s worth understanding this issue and looking at how you can avoid it by not making high level structural changes (if possible) or either manually deleting archives in advance or using software like CCC which will allow an advanced deletion pass.

              “FWIW, the other thing that TM does very poorly on is to be able to tell it, “hey, this drive went bad, so here’s its cloned replacement”.

              That’s because TM uses the UUID instead of the volume name. You can still replace a TM with a cloned drive, but doing so is a bit advanced… although having the need to do this is advanced anyway. I’m not making excuses here, but just explaining the issues involved. If Apple used the volume name, then any external drive with the same name would be identified as the TM volume. This is a problem considering pre-formatted drives are all named the same by manufacturer.

              Again, CCC runs into this exact same issue. Their solution, which is again, more advanced for power users, is to provide “use strict volume identification” as an option.

              TM is great, but if you need more power/pro features, CCC is really great too.

            2. @kevicosuave:

              I understand what you’re saying about high level structural changes which may depend on the level of the change and amount of free space, which does make some sense.

              However, the context that I’ve had TM drives bork on me has been in what I’ll call a “business as usual” mode, where I’m not adding tons of data or reworking existing data into new directories: it just stopped working.

              And what’s also weird about it is that I’ve been running two TM drives (then, both were 4TB) which was backing up what was then around 2TB of data in total (a small SSD and a 4TB RAID 0 ‘data’ array that was half full)…and the one TM choked on what should have been a trivial incremental backup – – figure <25 GB – – and the other TM drive … exact same size, mind you, backing up the same source … carried on its business for a couple of months before it finally decided to bork too.

              So if it was this "too big to dupe" approach, why did the one TM drive fail and the second TM drive didn't?


        2. I had my mac for over 6 years on TM backups, always upgrading to new mac versions 1week after release. Never ever did it actually delete the files, I noticed maybe 2 years later when the drive was close to capacity and that it seemed very strange. Come to find yet another apple bug hidden so deep. My love of apple is gone. Tim cook royally screwed apple. I actually went to W10 becuase of some high-perf programs and now shocked by how far they have come with UWP/XAML. Apple is screwed.

      1. C++, why are you giving apple a passing grade? Either you can trust a backup or you can’t. If Time Machine isn’t 100% reliable, it cannot be recommended. There are other ways to make a local backup.

        Once again Apple shows that it doesn’t care about legacy Mac users. Any app and any piece of hardware designed for PERSONAL. computing, which the user can manage, is now rotting on the Apple tree. Timmy is trying so hard to be a subscription computing service, it isn’t surprising that APFS wasn’t even tested adequately for local backups. This is the new Apple and it is a major disappointment.

      2. I am using a 240GB SSD as my primary drive. And an external 4TB as a time machine drive, and every time the 4TB fills up, TM fails to backup, because it doesn’t delete old backups. And this has happened multiple times, not just once. So it isn’t a viable backup system. I don’t use it anymore, and certainly never used it for primary backups. The interface is very cool though….

  4. I had this very issue. I converted my time machine to the new file format…and I lost everything. Had to redo my entire time machine drive again and backup everything a 2nd time. Very annoying that Apple didn’t have a warning of some sort to help users out.

    Tim Cooks Apple strikes again.

    I really miss the quality control that Steve Jobs brought.

    1. When OS X didn’t automatically upgrade the file format of my hard drives, I spent 90 seconds reading up on the issue before taking the drastic measure of forcing the upgrade. It didn’t take long to discover that Apple doesn’t, yet, recumbent APFS for spinning hard drives, and my 3TB Apple Time Machine. (which uses a spinning hard drive)

      Still, there should have been a warning when using Disk Utility.

  5. I’m no file system expert, but this really speaks to Apple releasing things that aren’t finished or not implemented fully. Apple needs to add “it just works” to their company statement – and follow through on it. If their excuse for not doing so is that nothing would ship, they need to re-think how they do business. I doubt this will happen as the way they do business makes ungodly amounts of money. So, I guess we just have to put up with half baked products and services (home pod, apfs, notch, all the bugs in macOS, iOS lately, etc.).

  6. This is why I have avoided High Sierra altogether and stick with Sierra on some machines El Capitan on another. Most software is still compatible with older OS’s and in fact desirable. For pro reasons I avoid it and also HS is simply not battle tested enough to be ready for prime time.

    Damn straight Apple needs to take a time out on new features and just get what they have working right. Making it as rock solid as Snow Leopard was. (Why is this the new normal of a couple releases are lacking and then Apple re-focuses on stability again. ‘Tain’t right. EVERY release needs to be worthy of being an Apple OS.)

  7. Yeah, I made the mistake of formatting a new external drive as AFPS with Disk Utility. The process failed and I was unable to format the drive in any format. I had to do quite a bit of research to find the solution—which involved digging in with the Terminal. I don’t mind doing that when I’m tweaking settings and such, but it should be impossible to break something with the Disk Utility GUI that can only be fixed by resorting to the Terminal.

  8. This happened to me, and it took a couple of weeks to straighten out (thank goodness for backups!), and with non-Time Machine disks. If you encrypt your disks, those will be converted during encryption as well, and there is no warning. A lot of software still doesn’t work very well with APFS, I would still recommend proceeding with caution and make sure you have everything backed up to your preferred format of disk. Cupertino really botched this one, and it is definitely still not quite ready for prime time.

  9. I still haven’t upgraded to High Sierra on my Early 2011 MacBook Pro or my new 27″ 4K iMac I just bought last July. At this rate I probably never will. Good grief what a cluster f**k.

  10. Even though you can change your boot drive to APFS in its menu within a few minutes.co thinking “cool!”, DYK the command+R recovery does NOT know what it is in terms of Disk Utility and it uses Yosemite for OS restore.

    After changing to APFS, I thought my boot drive was bad, so I ran out and got a 2Tb external and reformatted it as HFS+. Used the Time Machine backup. It worked, but still had the freezing issues. I reinstalled High Sierra using the “Download macOS High Sierra 10.13.3 Combo Update”. That stopped the freezing.

    I noticed with 10.13.3 installed, its Disk Utility showed the old HD WAS FINE, it just needed a repair. Command+R is useless if you have APFS.

    I’d rather have my boot internal. After erasing all signs of a APFS format, and a little swapping/deleting data, it’s back to “normal”. Anyway, I don’t regret the extra 2Tb (just $69) for the added space for my iTunes media.

    Now, I just have to fix Siri. It’s remained useless through all of this. I was hoping returning to HFS+ and refreshing of the macOS would fix it, too. Nope. Now, just Siri answers 1 questions, after closes, on the second access it will always “SiriNCService quit unexpectedly” errors then stops working. Even exploring a chain of Siri’s “open contents” results in dead ends. All I want is a new SIri and associated files. As usual, Apple is silent.

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