Mojave time machine back up failing

Maybe this can help

Fixed, Time Machine Stuck On Preparing Backup on Mac: Mojave & Earlier

This TM problem is beginning to be TS. But, just use a 3rd-party app such as SUPER DUPER, which can also be used to create a perfect OS X clone on a disk or hardrive.

I have used SuperDuper for many years and find it to be unmatched at cloning. It is an indispensable part of my backup strategy. I also use TM with a time capsule for automatic wireless backups but SD is my "go to" utility when disaster strikes. I will not be upgrading to Mojave until this issue is addressed however since backup is one of Apple's core philosophies and I find it irritating that there is a disabling bug in TM accompanying a major OS release. A lot of time can be wasted fiddling with a malfunctioning backup app before you realize it's a bug in one of Apple's core technologies. BTW - TM cannot be running at the same time as SD or there will be a copying error so turn off TM when cloning with SD

I was able to reproduce this issue several times with apple cares, senior techs. they took a snapshot of the failure and have sent it to the engineers. I think they now have everything they need to fix this bug. it took me several hours of being persistent, but it worked out in the end. Hopefully they apply a patch soon with this info.

Even if the case sensitive formatting allows the Time Machine backup to work, it would not be a fix, it would simply be masking an underlying problem because Time Machine is designed to work with both case sensitive and case insensitive HFS+ Journaled formatted drives, as it has for many years. I'm very anxious if anyone else sees the same behavior I have, which is Time Machine backup working 2 out of 2 times with case sensitive HFS+ journaled, case sensitive formatted drives. Since it started working it's been working fine for 2 days making successful incremental backups every hour without any errors. I'm as disappointed as anyone about Time Machine being broken, but having been intimately involved in all facets of software development for more than 30 years these things happen because of the massive complexity of software systems and the fact that no software is ever 100% tested for all possible conditions. Lots of moving parts + built by humans = something is going to break at some point. It's never a question of IF, only a question of WHEN.

I also tried to indexing Spotlight new, and it takes by now about 9 hours and have had about 25%, maybe there is also a problem with, or maybe this is the problem, because TM cannot check exactly what is changed and stops their.

Maybe you will test this also, i have 1,5 TB with 180 GB it should be much faster, ;-)

Even if you just partition a small portion of your drive it will at least give you some room to back up your mac. You don't have to erase your whole drive. Just a partition big enough to get you through until this bug is fixed. 😉 When they fix the issue, erase the partition and your back to the way things were. Easy peasy.

I hear ya. By chance maybe you should try a clean install, if you have not already. When i did a blanket update of mojave, it was kind glitchy in various areas. then i performed this method in the link below and lt has been buttery smooth ever since. (except for time machine bug) https://wccftech.com/clean-install-macos-mojave-ota/

I had the same problem with TM, and I believe you're right it's a Mojave problem. I've written an analysis that might help address some of your problems, too, particularly in re large and possibly fragmented files. What it comes down to is the file I/O process responsible for reading data may be getting stuck on things it thinks are corrupt.

Here's my writeup: Frequent system hangs and freezes in macOS Mojave 10.14: Notes, reproducible errors, and possible workarounds

Great work!

The lingering concern for me is how folder name confusion is related to case sensitivity, unless these are two separate issues in Time Machine.

The duplicate folder shown in Finder appears to have an extra non-displayable (in Finder) character but it should be treated as a totally different folder name in the file system. Case sensitivity doesn't even come into play. Any correct string comparison function would start off by first comparing the string lengths (strlen), i.e.,

if ( strlen("App Cleaner & Uninstaller") == strlen("App Cleaner & Uninstal?ler")) ...

From a string comparison perspective these names can never be considered equivalent. That would be a big problem for Apple.

Perhaps the "?" character in the second folder name trips up the file system string comparison logic? From a security standpoint this could very well be a critical error and exploitable vector that makes the Time Machine failures we've dealing with appear trivial by comparison.

I had this happen one of my external HD's recently so I rebooted and hit Command+R and once I got into Disk Utility I highlighted the external HD and used Firat Aid on it. It took what seemed forever but what was ailing the drive, First Aid fixed. Your mileage will vary. (It might or might not fix it) since Mojave is a different beast that High Sierra was with the new file system that Apple is using.

After wasting hours and days and reformatting drives until the cows came home (AND buying a new drive), I read this page about the crappy Time Machine for Mojave. Thanks a lot guys! I'll use SUPER DUPER from now on, geez! (And it makes a startup disk, too.)

I 2nd THAT! If Apple had announced the problem, it would have saved me months of wondering and weeks of anguish and the repeated reformatting of several hard drives trying to get TM to work! Not to mention buying a new external hard drive. Thanks Apple! Forget TM, buy SUPER DUPER or CARBON COPY, instead.

10.14.3 doesn't change anything.

Still growing up forever.

Got an answer from Apple though, after using BugReport. They told me to run a TimeMachine diagnostic command while the symptoms occur. At least that shows that they read the bug reports and don't ignore problems... yet.

But then they said it's normal it's growing up as new data is written to the hard disk.

This is totally wrong: TimeMachine is using RSnapshot. As the name tells it, it makes a snapshot of the disk and backups up this image. This is to avoid endless backup while data is dynamic. It's actually the exact opposite of what they say.

So I submitted the new diagnosis files. We'll see.