Time Machine stuck on Preparing? Try these solutions:
- Make sure that the drive is formatted properly (GUID for Intel Apple Partition Map for PPC’s)
- The fix seems to be opening System Preferences’ Energy Saver pane and un-checking “Put the hard disk(s) to sleep whenever possible.” Sleeping the iMac and waking it seem to cause no problem. Only the energy saver spin-down seems to have caused it. Several weeks on the “Preparing” hang hasn’t happened. Knock on wood.
- The fix appears to be to add your Time Machine disk to the Privacy settings of Spotlight so that it doesn’t get indexed and then reboot.
- I stopped Time Machine repaired permissions deleted the Spotlight index and let Spotlight re-index the drive rebooted the Mac and enabled Time Machine. It works now.
- Repair Disk from disk utility or FSCK -fy from Terminal
- Go to the Time Machine menu (activate it with System Preferences) and select “Stop Backup”. It will now stop the backup forever instead of prepare it but you’ve given TM some warning. Note that the System Preference panel and the menu will sometimes conflict; that is the menu will say “Stopping Backup” and the SP will say “Preparing Backup ” or vice versa. Ignore that because I’ve also found that System Preferences may not close properly while TM is in an endless loop.
- Disconnect/turn off your backup drive long enough for TM to realize that it’s gone. The volume will disappear from the desktop a “Device Removal” warning will be displayed (ignore) and the TM menu icon will change to an exclamation mark.
- Reconnect the drive. TM will now Prepare but only briefly and then proceed to back up normally.
Also try to keep the drive attached and on whenever your computer is on although this might be difficult for laptop users. I hope this helps someone!