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

I have been seeing this problem since installing macOS Sierra. It's happening about once a week with a 3 TB Time Capsule purchased within the last year. Rather than lose my backups and start over weekly, I added a second Time Capsule that is around 8 years old to Time Machine, and it works fine. Only backups to the new TC are failing. We haven't noticed any other problems with the new Time Capsule, and one other person here in the house is using it without seeing this error.

I'm suspecting some sort of problem with network error recovery introduced in the new OS version. The other Mac is plugged directly into one of the new TC's switch ports. My Mac is plugged into one of the old TC's switch ports. The home network runs through a gigabit switch and Cat5e cable in the walls. The TCs do not have NAT enabled.

Likewise, though I took the plunge to erase all old data. I've tried a ton of things without success. New backups to my 2TB time capsule (current model, about 2 years old) repeat the same error message, even immediately after new first backup completes.

I've erased the drive 3 times, I've reset the time capsule to factory settings, I've even tried Garth's fix (in posts above), but not being too techy these days I think I got something wrong as the sparsebundle threw a wobbly when I shut down. It did however say that the drive was dirty (which I found odd as it was after an erase and reset). Having followed Garth's steps I hope it is now clean.

First Aid said I had to fix in Recovery mode, but in Recovery mode First Aid found nothing wrong (rebooted and tried again, same result).

Now I've reset the TC again and am starting a new backup. The only thing I haven't checked since is whether the drive is now clean, but if that doesn't change things I simply don't know what else to try. I've backed up to a usb drive just fine, so I guess it's something on the TC disc (or something over wireless).

I've erased the drive 3 times, I've reset the time capsule to factory settings, I've even tried Garth's fix (in posts above)

Did you do quick erase or a full low level .. one pass?

I do strongly recommend the full erase.. but select just one pass. (ie zero out data).

This will take several hours.. but any bad sectors on the disk will be marked bad and if the disk is dodgy the SMART will trigger and you will get a bad disk error.

To mcb2k3

The other Mac is plugged directly into one of the new TC's switch ports. My Mac is plugged into one of the old TC's switch ports. The home network runs through a gigabit switch and Cat5e cable in the walls. The TCs do not have NAT enabled.

With the TC in bridge.. and a non-apple router running the show.. you can get into trouble with Apple's DNS.

Also because the TC will change IP constantly as it is renewed by the main router..

So what I recommend you try is static IP setup instead of bridge..

There are two parts to this.. you can continue to use bridge with simply using a static IP (or dhcp reservation in the main router). on the internet tab of the airport utility setup.. but I also recommend using DHCP server from the TC. And any switch is put behind the TC rather than in front of it.. so all IP addressing is handled by the TC.

Here is a write up of the setup with some screenshots.

https://discussions.apple.com/thread/5981989?answerId=25135547022#25135547022&ac_cid=tw123456#

This has helped a lot with system stability.

Even if you stick to using current bridge setup.. let me recommend you move the connection from WAN port of the TC to LAN. On the AC model airports we have found the WAN port can be unreliable with some routers.. in bridge the WAN port is assigned to LAN so there is no difference if you use a LAN port.. and it can help a bit. (I do think getting IP stable is of equal if not greater importance though)

I was going to say that both Time Capsules already have static addresses, but it seems that the new TC somehow "forgot" about that and went back to using DHCP, although it was still configured in the router as having a static address. I put it back and we'll see if that fixes it. Thank you!

Apple's DNS is different from other DNS?

No, if such a thing existed it would be the same as any other DNS.

Apple's DNS is different from other DNS?

Apple did make big changes at Mavericks.. and tried to fix it on Yosemite.. which was not wholly successful.

The DNS is somewhat different as it is wrapped up with bonjour and the setup with sleep servers.. is rather complex.. and more complex now with the swap to peer to peer when you a swapping applications between Mac and iOS.. (cannot even remember the technical name for it)

No, if such a thing existed it would be the same as any other DNS.

Bonjour is Apple only protocol and so it is different.

Then how does it resolve domain names differently from other Domain Name Servers.

Please read the discussion here.

http://arstechnica.com/apple/2015/01/why-dns-in-os-x-10-10-is-broken-and-what-yo u-can-do-to-fix-it/

Apple changed the whole DNS responder from standard used since 10.2

mDNSresponder to discoveryd daemon.. in Yosemite.

DNS still clearly does DNS but due to changes I think with this technology had to change.

http://arstechnica.com/civis/viewtopic.php?f=10&t=1152585

The Apple routers include a Bonjour sleep proxy which has been reported as part of the problem.. it is how all these things are glued together.

https://discussions.apple.com/thread/6010628?tstart=0

I cannot give you better than that.. read the articles.

DiscoveryD was removed in 10.10.4. Bonjour handling sleep requests has nothing to with Name Resolution and article 3 has apparently nothing at all to do with this.

Thank you - those links made for very interesting reading. The "Why DNS in OS X 10.10 is broken, and what you can do to fix it" article describes every home networking issue I have, and more, including hostname conflicts (not rare, though) and mysteriously disappearing Airport Expresses, problems that I have ignored because they didn't cause major damage.

I have also learned not to introduce Apple products, such as Airport Express or Apple TV, into the infrastructure of other networks I help maintain, because of the weirdness they bring with them. I prototyped a network expansion at a church I support using an Airport Express (brought from home) to provide Internet access along with a localized DHCP/NAT server for a digital sound system controlled via tablet over TCP/IP. The idea was to always be able to serve IP addresses to the audio equipment and clients in the building even if the Internet connection, which comes in over power line adapters from another building, went down. What happened instead was quite the opposite -- the Airport Express would go zombie every week or two and have to be power cycled. It was unusable.

Replacing that unit with a Netgear Wi-Fi router solved the problem, and saved the cost of an extra switch since it offered 4 LAN ports instead of 1. Fortunately, my Apple clients do still work. There are now 4 wireless routers/access points in the network, which covers most of 3 acres, none of them Apple because during testing Apple networking proved itself to be broken. And now I can more or less see why (I'm not deeply into networking).

I am glad to hear that I was not imagining these issues. I only wish the article offered a more acceptable solution. Having all your backups wiped out, weekly, is hard to ignore. I believe I had only seen this happen once before in the 7 years we have had this home network. I don't think the other Mac, that has not yet encountered this problem, is running Sierra. I guess we'd better not upgrade it.

I just spent 45 minutes on the phone with Apple Support. They are telling me that the problem is that I am also storing files on my TC... and it's not a "recommended use". Their explanation is that if I am accessing those files when TM tries to backup, then it may corrupt the backup leading to this error. (I pointed out to him that extra storage was precisely the reason I bough this thing, and it was on the advice of the Apple Store reps.)

They have told me to move stored files of TC to a separate drive, then reformat drive and begin again.

Regardless, this is the second time in a week I have lost all of my backups... considering this is a business computer, this is not acceptable at all.

Then in future treat your backup files seriously, dont cheap out by using the backup disk for other purposes, use it for one purpose, backup.

Thanks for this - very helpful. I have done as you said about 4 1/2 hours ago. Airport Utility on the mac only gives me the option to 'cancel erase' when I click on the TC (flashing orange and red 1), but Airport Utility on the iPhone6s is telling me internal disk needs repair.

I'm hoping that the TC will try and fix it all itself, but if not I guess it's a case of taking it back to a shop to sort out.

Re my post above, the TC hadn't changed status 12 hours later, stuck on reporting a problem. I'm assuming SMART couldn't fix it given what the iphone was telling me separately.

The local Apple affiliate shop tell me the error message means I have a dead duck and my only options are to either put it in for service, which they say will take 14 days and will probably tell me I need to buy a new model, or buy a new model now and be done with it.

I think my plan B (which I will probably stick with until a new model comes out) is to plug in a new external drive and use that as a backup drive. The wireless works just fine.

The conversation I had with apple support yesterday, pretty much said that (a) the "problem" was caused by the fact that I was using the TC as additional storage and if I access any of these files, it may corrupt the backup. (Contrary to what was recommended at the Apple Store when I bought the thing).

After I accepted I was going to need to move extra storage off this drive to a wired external, the guy told me that to backup my nearly 500 GB of data, that it should only take 4 hours or so. This contradicts what many have said in this forum. I am at 16 hours now and it's about half done. Based on what the Support Guy told me, this means the drive may be pooched.

I will let this run it's course and see how it works with incremental backups, but if I end up with this problem again, I will trash the TC and go to a wired external drive.

This situation may highlight the problem of having a wifi router and drive in the same box. Looks sexy, but it's an expensive fix when it goes down, since it isn't really feasible to be without wifi.

This is my primary work computer and I will confess that I am not impressed with this problem, nor the solution, because at the end of it all, I don't feel that I am any closer to understanding why the BU failure, and more to the point, I also don't have confidence that it won't happen again.