Time Machine not working since Mojave

Dr. Mac, I had the same issue (Mojave)...used disk utility, erased hard drive, tried over again and couldn't get Time Machine to work until...I turned off an outgoing firewall. Now Time Machine works. Hope something similar may help you.

scotsman

Have performed the same procedures as you have and keep experiencing the same problem. I even swapped to a brand new external hard drive and issue continues. Hope a solution is implemented soon, as it appears to be software related.

Hey Everyone,

I was having the same trouble, but, I reviewed this page https://www.lifewire.com/troubleshoot-time-machine-stuck-on-preparing-backup-225 9980 and found that the first time machine backup after installing Mojave is huge. So it takes a long time to prepare. BUT, if you have tried it and cancelled it, you probably have an open file or lock on the drive. So read lifewire's great write-up posted above and I hope this solves your problem like it did mine.

Cheers,

CtL

Since installing Mojive I cannot get Time Machine to work. The progress bar said "Waiting for first backup." However 494.42 GB of my old (last) backup with Immediately previous OS 10.12 is still on time machine. I went to WDmyCloud drive as "guest" and did another install. The old backup is still there. Now the backup has started again. It's on 99.49 GB of 434.52 GB after two hours. It still says."Calculating time remaining." Earlier today the backup climbed to 248GB and I left for work. I left the MacBook open and running. When I returned the screen was black with logos on it. When I entered my Mac password it did awaken. However the Time Machine had stopped and was "Waiting for first backup" again. Is there a command I might use to stop the Mac from sleeping so the Time Machine mught still continue?

It consumed more than 12 hours, but starting a new time machine installation on my Western Digital wireless MyCloud did a complete backup. The old backup with Sierra OS 10.12 appears to have survived as well.

Any solutions to this problem? I have exactly the same problem and have gone through the same troubleshooting procedures without any success. "Time Machine couldn't back up" ... "Time Machine could not create a local snapshot to back up from."

Erased Backup drive. Started again - no happiness.

Did the terminal commands to remove old snapshots - no happiness,

Tried other terminal commands - enable and disabling snapshots (apparently those commands no longer work) - no happiness.

...no happiness!

My installation of Mojave has also caused untold misery to my 500GB SSD MacBook Pro. Before installing 10.14 I had 72 GB of available space and a fully functional Time Machine with a Western Digital MyCloud wireless external 4.0 TB drive. After "Mojive" I had 3.1 GB available space and a non-functional Time Machine. It had lost my entire backup (or at least was not revealing it.) After a lot of random attempts he WD time Machine drive said "ready for first backup." It indeed backed up only 101.6 GB. The User file on my Mac showed 474 GB in it.

Remedy: 1) Acknowledge that when Mac OS 10.14 was installed, the Time machine essentially thinks you have a new computer & tries to start over. 2) Nonerasable giant user file became a huge file and reduced the available space to 3.1 Gb. 3) Call Apple Support direct, through the support web page or arrange for them to call you. They called me back an hour later on Sunday at my requested time. 4) If a level 1 tech has not encountered his before, ask for a level 2 person, like Harley. 5) Give her joint use of your Mac and watch some inexplicable magic. She used commands to reveal hidden files and commands that I could not begin to explain. In 32 minutes my Time Machine was working properly again and my User file was reduced to 101.4GB with a separate system file of 10.47 GB I have 374.62 GB available space.

I obviously do not know what she did to zip through dozens of commands & deletions. Perhaps some of you might follow the sequences! If, however, you are not at an expert level and just want a solution, please try the suggestion to call Apple. I just wanted my Mac back & running. I spent over 20 hours with no results on my own or with other solutions presented here.

I'm having this issue but not sure if my root cause is the same as everyone else. For me the issue appears to be caused by the iPhone back-up files (mine are encrypted). The issue started for me around the time I upgraded from High Sierra to Mojave. It's likely that the tech support gal deleted these files and is likely the reason your back-up is now working.

Background:

I interpreted the error message as having run out of enough local disk space to pre-stage the back process (ie snapshot). I proceeded to delete a ton of large files. This didn't solve my problem, so I then ran disk rescue, which took hours to complete. Once disk rescue completed I was able to finally complete a back-up and worked flawlessly for a few weeks.

It suddenly stopped backing-up again, same error message. So I worked through the steps I ran through previously. Having already freed up plenty of disk from the previous encounter I skipped this step and tried disk rescue to no avail, same bloody error message. I sat frustrated and decided to think backwards to what I had done different from the time that I originally fixed the issue and now. There was only one event that came to mind, I had upgraded my phone (from 7 to Xs) and in doing so had done various updates, syncs and backup of my old phone in order to transfer my data to the new phone.

My solution:

The iPhone back-up files being really the only recent addition to the system I decided to delete the files and re-run the failed Time Machine back-up. It worked, but why it worked I don't know. Maybe for some odd reason Mojave Time Machine couldn't read the encrypted (and password protected) iPhone backup files in order to create a snapshot. This would be fairly odd consider that it's iTunes that's handling the encryption and password protection.

So, if you're stuck, try deleting all of your iPhone back-ups.

Here is the tool you need: Time Machine Mechanic

https://eclecticlight.co/2018/05/31/new-version-of-the-time-machine-mechanic-t2m2/

a simple tool that reports on the success of the previous attempt to back up by Time Machine and isolates the error messages. My only helpful suggestion is copy and paste the error messages into a word processor so you can stick in some carriage returns to make it easier to read. Error messages are really dense text.

This tool quickly found that the conflict was with a single application, wrote to the developer, it was a known issue and he sent me fix instructions the next day.

DONE.

Thanks MB Steed

The following worked for me too - first time

Here is my solution:

TimeMachine Issue - unable to create a snapshot

Go to MacHD: Library: Preferences:

Delete com.apple.TimeMachine.plist

...then it worked fine.

I found a fix!

I offloaded everything from my Time Machine to an external hard drive.

Erased Time Machine using Airport Utility (link below for instructions)

https://www.macworld.com/article/1145617/business/timecapsulerepair.html

And then removed the snapshot of Time Machine

Go to MacHD: Library: Preferences:

Delete com.apple.TimeMachine.plist

And then tried the back up again.

Everything worked!!!

This first back up will take a bit.

Good Luck!

When I restart my iMac (Retina 5K, late 2015) running 10.14.2, the first couple of automatic Time Machine backups run just fine. Then things fall off the rails. It just stops running successfully. Automatic backups fail as do manual backups. I wonder if it has something to do with Energy Saver / waking up?

My work around is to be sure to reboot my Mac every couple of days so at least I have a relatively recent Time Machine backup but it would be very nice if it just worked like it did before upgrading to Mojave. Especially since I really haven't found a single feature or improvement one Sierra.

Here is my solution:

TimeMachine Issue - unable to create a snapshot

Go to MacHD: Library: Preferences:

Delete com.apple.TimeMachine.plist

...then it worked fine.

Huh, have the same problem you did. Had all the same thoughts you did to troubleshoot. Running without backup is no fun.