Update: I have resolved the back-up issue by uninstalling the WD Utilities program and removing other items associated with this program. There is an uninstall icon in /Applications for this. Additionally, I deleted the following that were not removed by the uninstall program:
/Library/LaunchDaemons/com.WDPrivilegedHelper.plist (this starts the WD Drive utility helper).
From the System Preferences>Users & Groups>Login Items, remove WDDriveUtilityHelper (this runs the helper when a user logs in).
After performing these actions, My Book has successfully executed Time Machine backups for 2 days with no issues.
What drew me to take these actions were:
- Determined the issue was not with Time Machine as I turned backups off, rebooted the iMac, confirmed with Finder that I could read from My Book (Backups.backupdb folder was visible and accessible). After a few hours, I could not access My Book with Finder (no Backups.backupdb folder).
- When automatically updating for the Sierra 10.12.2 update, an App Store notification window appeared stating “WDDriveUtilityHelper prevented updates being installed”. This was a flag that the WD utility program was the issue.
