Time Machine completed a verification of your backups. To improve reliability, Time Machine must create a new backup for you.

Now I also got this issue. I have a time capsule. Worse, it happened two times within a week. If it continues to happen regularly, time machine is worthless. And that's too bad. One of the main reasons I have stayed with Mac rather than Windows is time machine. My wife lost important data because Windows has nothing like time machine, whereas in the past I have been saved several times by time machine.

I have a MacBook with a single USB-C port, which is used for an external screen. So, I can only do wireless backup. If Time Capsule does not work I'm screwed.

I reported the issue as a bug to Apple and they now sort of recognised it is a bug, but I don't think they've got a solution. Here is what they wrote to me:

"This is most likely a software issue and not a hardware issue with the Time Capsule. We’ve see an uptick of new reports since Sierra that we are actively investigating. We now believe the majority of these are due to a bug that manifests on systems using PowerNap but your case may be an exception. Since the diagnostic logs do not cover the time of the original corruption it is impossible to say exactly what happened.

There's really not a safe way to continue using the existing backup history. You can mount the sparsebundle and try copying any files you need off of it, but once it has been corrupted there is no way to repair it that does not also risk damaging the integrity of your backup history."

I strongly advise you to use another way of making your backups. What I did is two fold:

1) Use Carbon Copy Cloner to backup complete disks on a daily basis

2) Use Arq to create cumulative backups (like TM), in my case to Amazon Cloud Drive

Hope this is of help to you

"This is most likely a software issue and not a hardware issue with the Time Capsule. We’ve see an uptick of new reports since Sierra that we are actively investigating. We now believe the majority of these are due to a bug that manifests on systems using PowerNap but your case may be an exception. Since the diagnostic logs do not cover the time of the original corruption it is impossible to say exactly what happened.

There's really not a safe way to continue using the existing backup history. You can mount the sparsebundle and try copying any files you need off of it, but once it has been corrupted there is no way to repair it that does not also risk damaging the integrity of your backup history."

I received virtually the same message from Apple....but it was a few years ago. The only difference was that "Yosemite" was substituted for "Sierra" in the message.

Since this error was originally reported in "Snow Leopard".....Apple has been "investigating" this issue for quite awhile.

I have never had any problems with Time Machine backups when the backup drive is connected directly to my Mac via USB or FireWire. The corruption issue appears to be tied almost exclusively to "network" drives.

My wife has a recent iMac and is backing up to Time Machine on a Time Capsule via ethernet. I am using a late 2013 MacBook Pro and backing up to the same Time Machine via wi-fi. Since we both updated to the latest versions of Sierra, both of us are getting the above cited error message about Time Machine backups. I have been ignoring the warning and not creating a new backup. On my wife's iMac, Time Machine still appears to have last backed up on March 24, 2017. After a previous failure last October, she lost backup data for the prior year. On my MBP, Time Machine shows my last backup today. From what I have read, there is no independent way to manually verify the quality of any backup on a Time Machine disk. I am sorry I bought the Time Capsule and will probably purchase two separate small USB drives for backups. Time Machine is way overrated and there are no recovery options whatsoever.

I'm liking that "Sierra / Powernap" theory. I've got a house full of Macs, new and old, all backing up to Time Machine, and I've gone through all generations of Airport/Time Machine without ever before seeing this error, until this past January 2017, when it showed up for the first time on the newest MacBook Pro (Retina, 15-inch, Mid 2014), with PowerNap enabled. And now I've seen it 5 more times since then, including twice in the last two weeks, as of this morning. All only on that one Mac. The backup drive itself is only a year old, and I never find any errors or corruption with Apple's tools or DiskWarrior. So, in the meantime, I've disabled PowerNap and am now, yet again, creating a new "first backup." I'll leave PowerNap disabled and see if I can't at least make it to the end of the year without seeing this ****** message again!

Yes this happened to me a week ago and I let it rebuild. Now it has happened again. This is ridiculous: it is like having no short-term backup at all. Attempting to enter Time Machine just causes the screen resolution to change and garbage the screen, so no longer have any access to my backup.

Recommendations for an alternative backup hardware/software/protocol - ignoring Apple products - would be welcome.

It now happened third time

Csound1 wrote:

I have been fortunate enough only to have had that message once, I replaced the drive and have not seen it since (3.5 years)

It now happened third time for me within a few weeks, so the backup system is useless. I have a time capsule. How could I replace the drive?

Time machine has been so helpful in the past, saved me several times. Now it's useless.

I went back to using my old G-Drive mini on my MacBook, but now I will have to buy another one for the second MacBook in my house. So my Airport is now just a $400 WiFi transmitter.

Very disappointed that Apple cannot solve this with a software update.

I just got this message on a late-2013 13" MacBook Pro Retina backing up to a 2TB Air Capsule. Didn't know what to do so it's now doing the painfully slow new backup.

But: What is the worst thing an automated backup program can do? Destroy all your backups without offering any recovery option "to improve reliability". And that's what this program does. Get to work on this Apple. It's not like the Time Capsule is cheap. Earn your margins with reliability and functionality!

And now its happening every few days. I'm done. I will check out Carbon Copy and Arq. Very disappointed, Apple!

I don't see that a pice of backup software can be considered "the best of a very small lot" when it proceeds to destroy all backups from time to time. Which other choices offer this as a (non) option?

I also had the dreaded message (MacBook Pro - Sierra latest version - TC wireless connection) and twice rebuilt my backup in about a week. After going through the comments here I deleted PowerNap and have for nine days not had a further problem.

But I have been able to reproduce the "crash" that followed - with failure to enter TM and the screen resolution changing to 1970's pixel sizes. It can be achieved by trying to enter TM when there is limited disk memory remaining. That's not a very friendly way to deal with the problem Apple, so another indicator that TM is not very robust.

tjbarry wrote:

I don't see that a pice of backup software can be considered "the best of a very small lot" when it proceeds to destroy all backups from time to time.

You are free to pick whichever alternative you want to.

I think the problem may be having both ethernet and wifi enabled.

I had had no problems in the past and was blaming sierra, but then came across a post on another forum mentioning backup problems with both network interfaces enabled.

I only turned on wifi since installing sierra so that Siri could tell me the weather and I could unlock the Mac with my Apple Watch. ( For some reason it needs both bluetooth and wifi enabled )

I have just turned wifi off a couple of days ago so it will take awhile to see if this has fixed the problem as it would occur every 2-4 weeks.

I think the problem may be having both ethernet and wifi enabled.

Unfortunately, that is not the problem. It will not be long before you see the message again.

If it was something as simple as this, don't you think that Apple would have issued a support document about this long ago? The problem has been with us since Snow Leopard, but it is much worse with Sierra.

Regular calls over the past 5 years to Apple Support have always resulted in the same answer........"We're working on it". At this point, it might be wise to pick one of the following choices to help you decide if you want to stay with this.

1) Apple has been "working on it" for over 5 years and still doesn't have a fix, but we can hope.

2) Apple was at one time "working on it" but is no longer doing so.

3) Apple never was "working on it".

Add to this:

4) Apple will never be working on this

I don't think the discussion about having both Wifi and Ethernet enabled is relevant for this problem. I have been using Ethernet only for Time Machine and never had any problem, until Sierra..

I have been a dedicated solely apple fan since the Panther Days. I have all Apple computers in my home from Mac Pro, 2 iMacs, MacBook air, 2 MacBooks, 2 iPads, 2 iPad minis, 3 iPhones, 3 apple tvs, airport extreme, airport express, apple watch, i don't even remember what else is lying around. I feel the time has come to find a new company as apple as not been the robust innovating company they once were. They do not seem dedicated to their entire lineups and don't seem to care about the major frustrating issues such as this. Are there any good suggestions on other hardware?