update failed -16

This is a strange one, since error -16 normally appears when there is an error during the restoration of an iPhone or iPad from a backup....and I cannot find any other information about this error.

Try the following......if you have not done so already:

Pull the power cord from the back of the Time Capsule

Wait a few seconds

Plug the power back into the Time Capsule

Allow a full minute for the Time Capsule to restart

Restart your Mac as well

Report on your results.

Time Machine has a way of wanting to start over with a new "master" backup after anything out of ordinary occurs. Nature of the beast, I am afraid.

If space is getting tight on the Time Capsule, you might want to stop the backup and then erase the drive and start over again with a new backup. A wired Ethernet connection between your Mac and the Time Capsule will likely take half as long or less than wireless.

If there is plenty of the space on the drive, you can let the new backup run. Once the new backup has completed, if you want to get into the "old" backup to pick up a file, you will likely have to perform a few tricks as follows:

Right-Click on the Time Machine "clock" icon on the dock

Click Browse Other Time Machine Disks

Click on the Time Capsule drive