Trouble with Timemachine

I had the same error this weekend. I decided to abandon the old backup and start a new one. You do this by turning off time machine, then browsing to the drive with your backup and renaming whatever.sparsebundle to whatever.sparsebundle.NOT. Just say ok when it complains about the file type. Next you go in time machine preferences and pick the disk for your backups all over again. This is starting from a clean slate. If this doesn't suit you, other options involve a spending a LOT more time using disk utility to check and repair the sparsebundle. I've never had good results after wasting all that time hence my suggestion you get a new backup started right away.

Also, don't let time machine be your only backup. This is not a good idea. When TM works, it's great. I've had TM fail miserably and luckily I had things backed up to crashplan or my wife would have lost all her files. A few years ago, the power supply in our 1st gen TC died. Apple replaced it for free but the new TC came back empty so all my daughter's files were lost because she had a disk wipe during the time the TC was out for repair. That was the last time I relied on a single backup solution.

 

This could possibly be your Network having problems.
Not something to worry about really.
You just need to make sure your Mac device is turned on throughout the entire process of the back up.
And if all else fails, get a hard drive and do it on that.

 

That is exactly what happened to my daughter's files. That is exactly what happened to my wife's files except by the time the TC monster ate my wife's files, I had learned the lesson from losing my daughter's stuff and I had already invested in another backup solution so nothing was lost.

The issue is that TM is still a work in progress and when it works, it's great. It may have been introduced with Leopard but it's still not quite right. It doesn't always work.

Heck this weekend my Macbook Pro told me it was time to start over which is a nice way to say my 197 GB TM backup was now crap. Ok fine. I let it start over. Only it failed. I came back in the morning to a login screen. My MBP had crashed overnight and never finished the TM backup. I was staring at an all-too-familiar clock icon with an exclamation point on my menubar.

This time I forcibly renamed the sparsebundle so it could create a fresh one and the backup succeeded. If you think these stories are opinions, then you go ahead and rely on TM and TC for your only backup. Perhaps 5 months from now we will be reading a thread about how you "lost everything" and "nobody warned you". Well some of us are trying right now.

And no this isn't intended as an indictment of Apple quality. It's common sense not to rely on only one safety net for something that's really really important... like the contents of Macintosh HD.

BTW, that new ML feature to allow multiple backup destinations is a big deal. It's unlikely both of them will be borked at the same time, especially if one is a local USB or FW drive and the other is a network drive so we might be arriving at a time when TM can be your "only" solution as long as you have no fewer than 2 active backup destinations.