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User profile for user: JDL1537
JDL1537 Author
User level: Level 1
4 points

Time Machine stuck on ‘preparing for backup’ for 12 hours

I have a iMac 21.5 inch 2019 model running Mojave 10.14.5 and have been successfully doing backups with Time Machine for the last 3 months.


However when I tried to initiate a backup earlier today the backup did not execute as normal, instead the ‘preparing for backup’ stage, which normally just lasts for a few minutes, has been going for over 12 hours.


i do not understand why this is so, as I have only added maybe 3 GB of data since the last backup.


My questions are:-


  1. Why is the ‘preparing for backup’ task going on for so long?
  2. Should I just keep waiting and hope that the actual backup task starts soon?
  3. If not, what do I need to do to carry out the backup?

iMac Line (2012 and Later)

Posted on Aug 27, 2019 4:08 AM

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User profile for user: dwb
dwb
User level: Level 7
33,082 points

Posted on Aug 27, 2019 11:17 AM

9 times of out 10 the solution for TimeMachine being stuck in Preparing can be fixed with these steps:

  1. go to system preferences, select TimeMachine and turn TimeMachine off.
  2. Double click the TimeMachine drive icon, double click the backup.backupdb folder, and then your computer's folder. You are now looking at a list of backups by date and time. Click on the sort column to get the most recent backup at the top of the list.
  3. The top item should now be Preparing.
  4. Drag it to the trash and empty the trash
  5. return to System Preferences and TimeMachine & turn it back on


If this doesn't work, launch Disk Utiities, select the backup drive and select DiskFirst Aid

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User profile for user: dwb
dwb
User level: Level 7
33,082 points

Aug 27, 2019 11:17 AM in response to JDL1537

9 times of out 10 the solution for TimeMachine being stuck in Preparing can be fixed with these steps:

  1. go to system preferences, select TimeMachine and turn TimeMachine off.
  2. Double click the TimeMachine drive icon, double click the backup.backupdb folder, and then your computer's folder. You are now looking at a list of backups by date and time. Click on the sort column to get the most recent backup at the top of the list.
  3. The top item should now be Preparing.
  4. Drag it to the trash and empty the trash
  5. return to System Preferences and TimeMachine & turn it back on


If this doesn't work, launch Disk Utiities, select the backup drive and select DiskFirst Aid

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User profile for user: rkaufmann87
rkaufmann87
User level: Level 10
143,392 points

Aug 27, 2019 6:09 AM in response to JDL1537

It could be a problem with your HD however first reset the NVRAM and then restart in Safe Mode. Disconnect all peripherals (including your Time Machine drive) when doing these. Then restart normally and test.


PRAM and NVRAM Reset

Use safe mode to isolate issues with your Mac - Apple Support


What brand of External Hard Disk do you use for your Time Machine backup??????????




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User profile for user: rkaufmann87
rkaufmann87
User level: Level 10
143,392 points

Aug 27, 2019 1:10 PM in response to JDL1537

Well unfortunately WD enclosures have a pretty dismal reputation in these forums. If you determine it is the drive, then I'd recommend replacing it with an OWC Mercury Elite Pro, this is the drive many experienced users on these forums use. They are highly recommended due to their reliability, reasonable cost and the ease of service if the drive needs replacing. You can find them at https://eshop.macsales.com/shop/owc-mercury-elite-pro/usb-3.1 the are available in capacities from 1 - 14TB.

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Time Machine stuck on ‘preparing for backup’ for 12 hours

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