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Time machine freezing at preparing

My time machine has been backing up fine until recently. It now freezes at preparing stage. I checked the external disk in finder and the prep file shows it stops at 32kb almost every time. I've let the backup run for as long as 18hr and no change. I've tried the suggested trash the prep file in finder, etc.. No change! I've tried it with different external drives. No change! I went out and bought a brand new backup drive, it backed up twice and then back to the same issue ! My internal drive is partitioned, and on one drive I'm running Maverick, and it backed up no problem, on my other drive I'm running 10.15.7 Catalina and this partition is the problem. I even reinstalled Catalina, and NO CHANGE! I've ran disk utility on all drives, and all check out. My suspicion is possibly it might have been shut down in the middle of a back up, but i'm just guessing...i called apple and no help there, and their answer is It's an old OS system, etc... Well so is Maverick and it works. I'm running a late 2013 -27 inch iMac, with a 2yr old 3TB hard drive, partitioned in half, 32GB of memory... This is very frustrating as I'm in the middle of a big project and can not afford to lose my ongoing work....

HELP! thx.

iMac 27″, macOS 10.15

Posted on Oct 11, 2024 10:57 PM

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1 reply

Oct 12, 2024 6:33 AM in response to sparky2u

For reference: If Time Machine remains in the preparing stage on Mac


TM may be stuck at a specific file. Determining which file is obviously tedious. You can use the following shell script to potentially identify it:

clear; printf '\e[3J' && log show --predicate 'subsystem == "com.apple.TimeMachine"' --info --last 8h | grep -F 'eMac' | grep -Fv 'etat' | awk -F']' '{print substr($0,1,19), $NF}'


Use Terminal. Select the entire line above (triple-click to select the entire line), Copy and Paste then Return.


Be advised I no longer have any Catalina systems on which to test that script, but it is harmless. It extracts certain potentially relevant excerpts of Time Machine's log file. As always exercise caution whenever using the Terminal app, but worst thing that can happen is the above script won't reveal anything actionable.


Terminal User Guide for Mac - Apple Support


Post the output of that command. To do that in Terminal, Edit > Select All, initiate a reply to this Discussion, then copy and paste then Reply.

Time machine freezing at preparing

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