Mid 2012 MacBook Pro stuck on “Preparing backup” in Time Machine but can’t update to Big Sur

Hi,

How long have you waited for TM? It can take hours and depends on the size of the data it has to back up. How much data is on your internal drive?

You could also stop the process, erase the external drive as GUID and Mac OS Extended (Journaled) and start over. I would give it at least overnight to see if it works.

I had a 2017 MacBook Pro that's having the same problem. It's been stuck in the same position of "Preparing backup". I do have a large amount of content to backup, about 2.5TB, and it's taken about 7 hours so far. This is the second time I tried to do this, the last time I had left it overnight and it's still in the same spot.

Does it interrupt the process of the computer falls asleep? I didn't see any control that allows me to prevent it from doing so.

Jmqthechameleon wrote:

I have a mid 2012 MacBook Pro that I’m trying to get a recent backup of but Time Machine is stuck on “Preparing backup.” Most troubleshooting solutions say to update the computer but I can’t update to Big Sur because it’s too old. I’m in limbo. How can I backup my laptop so I can transfer my data to my new MacBook Air?

You may have a smoother transfer/migration process with a Time Machine backup, but if you are having trouble with Time Machine (I would allow it to run overnight) you can also transfer or migrate with a "clone" type backup, using a program such as SuperDuper or Carbon Copy Cloner. Those simply duplicate your original drive to an external drive. If you are running Catalina or earlier, the external drive should be HFS+/GUID, but if running Big Sur or later it should be APFS/GUID. The Apple Migration Assistant with the new Mac can transfer your accounts and files from the old Mac's backup. There is a version of SuperDuper that is free, it does not have all the options versus the paid version, but it will do the backup you need. I recommend the paid version, it is a useful program to have. Carbon Copy Cloner also can do this as can various other third party products.

Since your issues with Time Machine might indicate other "issues" with your old Mac, I suggest migrating only user accounts and files but no software and no settings from the old Mac to the new Mac. Then reinstall from scratch software and settings that you use.

I was finally able to get the "preparing backup" message to go away. It seems my backup drive had to be formatted APFS, since I'm running Big Sur. Now Time Machine seems to work as intended, EXCEPT every time it tries to backup it crashes my computer. It takes down the whole machine, giving me the black screen with the "Your Computer Crashed Because of a Problem" message. Obviously, this is a major issue. Any idea why that might be happening?

I had set up my backup drive with a password, like the Mac OS suggested. Could that be tripping Time Machine up?

Elliot Taub1 wrote:

I was finally able to get the "preparing backup" message to go away. It seems my backup drive had to be formatted APFS, since I'm running Big Sur. Now Time Machine seems to work as intended, EXCEPT every time it tries to backup it crashes my computer. It takes down the whole machine, giving me the black screen with the "Your Computer Crashed Because of a Problem" message. Obviously, this is a major issue. Any idea why that might be happening?

No.

Password (for encrypting the TM backup?) shouldn't be an issue, it's made to work like that.

I would start from scratch again.

Go to System Preferences > Energy Saver > check the box for "Prevent computer from sleeping"

There is no "energy saver" menu in my System Preferences, but I did find something under battery that looks like it addresses the same thing... So it does interrupt the indexing if it sleeps?

You must be running Monterey, not Catalina? Yes, if computer sleeps, I believe it's interrupted.

Oh yes, sorry I didn't specify. I'm running Big Sur.

Ok, thanks. That explains Battery instead of Energy Saver.