Sierra and Time Machine

For me it wasn't "stuck" on "Preparing backup...". It just took a while for the first backup after the upgrade. The upgrade modified a lot of files and I guess during "Preparing" it collects all the information on files which have been modified. On my old 2011 iMac the first backup after the upgrade was extremely long. First it was "Preparing" for many hours and after that the backups also ran for many hours. I think in total it took more than 24 hours but I didn't monitor closely.

After that backups are all back to normal and as fast as they have always been.

On my newer iMac it was also slow but I let it run through the night and the next morning it was back to the normal backup schedule.

So maybe it's just that the first backup after the upgrade takes much longer then usual. I also found some log messages in console which suggest that Sierra does some "migration" on the backups which may require additional time.

Completely new backups to new drives are much faster as it simply backs up everything and it doesn't have to handle the old backups either... But otherwise, patience is maybe what it required for the first incremental backup after the upgrade.

good it worked in your case - i have a fast machine and it was stuck backing up for 4 days and it never completed it.

I tried all of the mumbo jumbo of resetting the machine, formatting the external hard drive - nothing worked except uninstalling the antivirus (in my case Avira). after that everything was back to normal - nut now I'm stuck without an antivirus 😟

Encountered the same 'preparing backup' message without any apparent action.

Tried an earlier suggestion of [option]_Time machine icon in menu to do a'verify backup' and after that completed, tried to do 'backup now'

Did the 'preparing backup' and finally after around 5 mins started the back albeit very slowly suggesting it would take 5 hours but now showing 3 hours. So expecting that while it will take some time, it will do the backup.

I just installed macOS and noticed the same exact behavior - slow Time Machine backup. I turned off optimize storage in iCloud. This made some improvement. But, when I paused iCloud Photo upload from the Photos application, I believe that this made Time Machine backup as quickly as it did in previous OS's.

It kind of makes some sense after reading this KB from Apple.

"Time Machine is designed so that it doesn’t interfere with the regular operation of your computer. If your Mac is busy, hot, or the battery is running low (portables only), Time Machine slows until your Mac is idle, cool, or charged."

For those interested...

I have problems with "preparing backup", MBP running hot and very slow data transfer to my Time Capsule after upgrading to Sierra.

Tonight I have removed the old backup file which was 1Tb and now a new backup is running at normal speed, just like it used to do before the upgrade. Problem solved...

This one fixed it for me! Deactivate "Optimize Mac-Storage"! Thank you so much!!

I have tried pretty much everything on this forum. Preparing back is still taking a long time but not as long as before. Now when it backs up, it goes well then it stops at some point and simply hangs there. Once it stops it will not start again, not matter what I do. It is incredible that Apple would put out such a major upgrade without making sure that it was compatible with Time Machine. If you are reading this Apple, get your act together and produce and update that will solve this. I will go back and redo everything and see if I can actually get one full back up.

Kaalass wrote:

I have tried pretty much everything on this forum.

Including starting your own Discussion? If you already did that, I can't find it.

Nope. I posted in this discussion and got several replies. Like I said I tried the suggestions. There were improvements but after the upgrade back ups are still not smooth and quick as they were.

Kaalass wrote:

Nope. I posted in this discussion ...

Then you did not post your own Discussion.

Doing so is the best way to receive helpful, accurate, and timely responses to your concern. To learn how to do that please read Writing an effective Apple Support Communities question.

Ok. Thanks.

i have the same problem, after a long time trying all the suggestions, uninstalling Antivirus and all other tips

now my TM backup says clearing old backups, after always saying preparing backup

does tis mean it works now ?

it stays for hours now in the clearing old backup mode

Check the "Activity Monitor" in the Applications - Utilities folder and see if backupd is running, i.e. has some % CPU time. However, it shouldn't be at close to 100% for most of the time either...

Also check the "Console" in the Utilities folder and search for messages of "backupd" or messages containing "TimeMachine".

Maybe this helps to see if it is hanging or working...

Hi the solution is Antivirus Program stops Time Machine from Working

i even had to uninstall my Avira Programm to make Time Machine working

So in conclusion Sierra have a Problem with diff Antivirus Programms

Would that things were so simple Bob. I had the problem without any antivirus installed, so it may be a factor, but as is often the case where file management, OS and network change, it's clearly multi-factoral.

For me, disabling iCloud file management worked, for you, it was a/v.

The real disappointment, as usual was Apple's weak response, but we're used to that.