The backup disk image “/Volumes/Data/iMac.sparsebundle” could not be accessed (error (null))

Hello Linc. This same error message came up for me out of the blue with mid-2011 27-in iMac using OS 10.13.2. Followed your directions. Still not able to get into Time Machine. New error message reads: "Time Machine can’t connect to the backup disk. The operation couldn’t be completed. (OSStatus error 5.)". This message occurs after being prompted to enter my password (which i do correctly) to the command "Enter your password for the server "X" AirPort Time Capsule so that Time Machine can assess it". Can you help with what's next to get Time Machine working again?

Try shutting down you Time Capsule and unplugging it for about 1 minute. Then reset the SMC on the iMac per Intel iMac SMC and PRAM resets and then restart the iMac and restart the TC and re-test Time Machine.

Can you mount that disk image in the Finder?

Please delete the backup destination in the Time Machine preference pane, then add it back. This action will not cause any backups to be deleted. Test.

Yup, I've got exactly the same hardware, just running 10.11.4.

Exactly the same problem started 3 days ago.

Linc's solution solved it!

Thanks so much, you aint half clever!

J

worked for me to, Thx

Hi Linc. You fixed worked! Ended up having a password problem to access Time Machine server which I resolved and it started working again using your suggestion. Thanks!