Apple - Time Machine failing to complete backup

I guess that TimeMachine cannot unmount its snapshot, tries only once, and cancels the backup. If it happens, try to identify your mounted disk (e.g. /Volumes/com.apple.TimeMachine.localsnapshots/Backups.backup‌​db/namehere/2017-11-‌​13-202006/Macintosh HD) and then do

sudo lsof /Volumes/<Your Disk> 

and see which process interferes.

You could also just guess at Spotlight being responsible and disable it before you run the backup using

sudo mdutil -i off /path_to_volume

or completely

sudo launchctl unload -w /System/Library/LaunchDaemons/com.apple.metadata.mds.plist

I have the same problem after updating to OS 10.13.2

Turning off Spotlight with

sudo mdutil -a -i off

allowed the Time Machine backup to finish.

I then turned Spotlight on again with

sudo mdutil -a -i on

I hope the next OS update fixes this but.