look in finder sidebar. this message indicates that the virtual volume with your TM backups is already mounted. eject it and you should be able to back up. to initiate a backup manually go to TM menu in the menu bar and select "back up now".
I also has that same thing happen. I'm using the airport extreme and an external HDD connected to that for time machine. I resolved the issue by unplugging both the HDD and router for a few seconds.
The proposed "solution" (to unplug/restart the router/disconnect users from the disk) isn't really a solution, though. Rebooting the network every time Time Machine breaks itself is hardly a solution. The whole system is supposed to be worry free; a network reboot is hardly an example of worry free.
The problem is silly and rampant on my home network that servers a collection of laptops; at any given time, someone seems to be seeing this error. If we wait long enough, the problem seems to go away, but in the meantime, people are unable to back up their machines.
My best guess as the cause of this problem is when a laptop is put to sleep in the middle of a time machine backup. Since time machine effectively runs as a background process, this occurrence should not be surprising and should have been handled gracefully by Apple. Except it (apparently) isn't. When the machine is slept during the backup I again guess that lock file is left in the sparse bundle. My attempts to find said lock file have been unfruitful.
I'd sure like to see Apple address this issue in some way.
Sculler1x wrote:
I've been having the same issue and have been doing the Reboot of my AEBS and Hard Drive. Not an ideal situation! Has anybody made any headway!?
