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

I am amazed that this is still a problem, after four years of existence.

Apple's Time Machine solution has two functions. One is to make sure you have a backup and the other is to allow access to older versions of your data.

But periodically, TM must delete the old backup entirely (so if your machine fails during the recreation of the backup, you lose all your data) which also has the side-effect of losing all the previous versions of your files.

So bluntly put, Time Machine does not achieve either of its primary goals, and never has.

That is correct.

Running Maverick Server - has multiple directly attached (thunderbolt) drives. One (8 TB) is or media share (Massive Itunes library) and the other is for time machine central backups. SInce I went to Apples Server product this issue is even worse. I have had centralized backups for 3 years, without server, and never had this issue but one time in those 3 years. Now that I have gone to a product that should support it better (Server) i get the following:

Got 3 macs backing up to the server and every 3-7 days they each need to start over with new backups. Some of these are wireless and that ain't gonna happen (too slow and disk intensive). I am offically done with time machine and am looking at alternatives.

Our backups are the one thing you should never lose. I am a Senior SQL Server DBA for a large financial institution and if we had issues like this with a product from Microsoft they would jump on it... you do not lose data.

And no, Apple - there is nothing wrong with my drives. I reapir them and they come up clean etc. The problem is you crappy time machine software.

With the greatest of respect, Mavericks Server is not something you want to rely on.

I persevered with it (OS X Server) for years and it was just too unreliable. Functionality seemed half-finished in pretty much every release and I never found a stable configuration, even on as vanilla a server as I could muster (no non-Apple apps, no GUI users).

The straw that broke the camel's back came when Apple "improved" OS X Server to the point where it would (presumably leak memory until it would) hang completely. Crashing is great because it can reboot itself and services are only down for a few moments, but hanging - sorry no. I was visiting my "server room" every week to physically hold down the power button.

Apple Server Software - just say no.

I feel your pain re Time Machine. Software which periodically chooses to delete all your good backups to expose you to the risk of hardware failure and total loss of data is not a backup solution - it's a backup problem.

Yip I am having this problem too. What a nightmare!

Same here on a IMAC and an MBP using Maverick and Seagates businessstorage 2-bay nas connected through the internet. No such problems with a usb3.0 connected samsung exteranl disk!

Suffering from this issue too. MacBook Air running the latest version of Mavericks, and my backup device is a Raspberry Pi running the Linux AFP server to serve itself up as a suitable backup destination for time machine backups.

It seems to be happening once every month or two for me at the moment and as others have pointed out it makes Time Machine useless if you can never really have backups more than a month old! In my case it's really for worst case scenario's and as long as I have A backup, if the internal SSD dies then I'm covered. But it also makes me mistrust the integrity of the backups - can I even depend on them?

I flat out REFUSE to pay for a Time Capsule because they're so ludicrously overpriced. Why can't Apple make this work properly! Time Machine was always one of those features that I mentioned to friends who were unsure about MacOS as being one of the best features - quick, seamless backups - just switch it on and forget about it. My faith in the feature is being quickly eroded 😟

Yes, it has hit me for the first time too. Having used Time Machine for one of my backups ever since it came out. This is on Mac OS 10.8.5 on a MacBook Pro Retina mid 2012, using a Time Capsule Model A1470 (latest model) software version 7.7.3 (latest). Backup over the air. In contrast I have a backup on a LaCie Rugged mini disk (1TB), using zfs as the file system (zevo 1.0.3) - no problems whatsoever, full scrub (checking every single byte) returns with no errors, have done parallel backups to Time Capsule and this disk, for a longer time on the external disk. I'd really like to know what is going on here - I too find it unacceptable for a backup to end up in this state. PLEASE give us ZFS as a file system in your next OS release Yosemite, Apple. Until then I am likely to stay on 10.8 for the capability to use zfs (https://en.wikipedia.org/wiki/ZFS)

This message I have just received for the first time tonight - just short of 12 months after I bought my Time Capsule (currently running firmware 7.7.3). The message came up on an iMac 27-inch, Mid 2011 model running Mountain Lion 10.8.5. I've been into Time Machine and everything looks ok. The Time Capsule has been working fine until today. Have two other machines backing up to the same TC - a MacBook Pro and an iMac G5 running 10.5.8. What do I do?

Following up on my last message, the problem is limited only to my machine running Mountain Lion 10.8.5. The other two machines running Leopard 10.5.8 don't have a problem with their back ups to the same TC.

Happened to me as well. Backup was running fine fore more than 2 months to network drive but today failed. What i noticed it could be related to wifi connection. Normally i'm connected using ethernet cable and thunderbolt port. Yesterday i've unplugged net cable as well as charger (just to move to different room) and noticed backup was running during that time. Nothing really happened, backup finished, everything was looking good. Next day received messages and couldn't continue with backups. Backups were accessible and i could see the files. Since didn't have much (2 months of backups) i created new one. So far everything works fine.

I also got this message after only a few days of using TM to backup my new Macbook Pro to a USB drive attached to a new TC. Very annoying indeed, and apple should definitely address this problem. My work around is to rename the old backup and then have the TM create a new one. Once TM completed creating the new one, I'd delete the old one once I'm sure I don't need it. I guess you could also copy the old one to another disk to make space for TM. As many of you have said, the old backup, while considered inconsistent by TM, is still good and can be read by the Mac OS. Again this is just my way of working around the problem, not really a solution.

This just happened to me as well on a 2013 MBA and new 2TB TC that's been working just fine for almost a year now. Seems like this problem goes back pre-Mountain Lion. Oh well, so much for that...

I had this problem before (12 months plus ago?) on a Macbook Pro connected to a Synology NAS over wireless. Backing up over a direct Ethernet connection seemed to make the problem go away. Then I went back to using wireless and it seemed fine. Suspected a new release of software on one of the devices fixed it

I've now got a MacbookAir (Yosemite) and its just thrown up the same problem. Did its first back-up to its own partition on the NAS and the following day has come up with the error message. Now in the tedious process of seeing whether a repeat of the backup will solve the problem.....

Pity that Apple does not seem to have a more helpful response to this problem that has been rumbling on for years. At least to give a better anaylsis of possible causes. The consequences of losing your back-ups are too serious to contemplate but Apple does not seem to be taking it seriously, judging by the lack of responses

I've been having the same problem for some time now. I've reached out to Apple, and yeah, it's a pity....they won't acknowledge there IS an issue. But quite clearly there is. It's getting frustrating when we pay SO much for Apple products, only to have less and less support! IF Apple is moderating, WHY won't someone hop on and say SOMETHING!

I haven't been able to back up my iMac in months because of this.