I am getting this message when Timemachine tries to back up.
The backup disk image “/Volumes/Data/Lucio Bernal’s iMac.sparsebundle” is already in use.
Does it have something to do with Moutain Lion that I just installed?
I'm on Mountain Lion and have version 6.1 of AirPort utility so there is no button to "Disconnect All Users" (as you point out on your site) and the only other option of "removing and re-selecting the drive via Time Machine Prefs" didn't work either, so I posted this here because in the end this was the only way I could get TC to work again. The "Enable File Sharing" button seems to have replaced the "Disconnect All Users" button but with the slight disadvantage that it reboots the TC which takes up additional time but at the end of the day this surely has to be better than simply pulling the plug!!
I'm more curious as to how I ended up with this problem in the first place, all I'd done was a reboot!!