I updated to Catalina 10.15 about a week ago, and I noticed the Time Machine backups do not seem to work properly. Yesterday I thought I'd try to make it work again, but the problems I face are so weird!
The backup goes through the "Preparing backup..." with no errors, and then it starts copying files. When it has gotten about two thirds of the way through the 17 GB (I'm guessing it's so large because of the update) it just quietly stops, without any error message. If I check for the backupd process in activity monitor, the CPU usage is at 0.0 and never increases. Also the drive will stop spinning after a while, so clearly nothing is written. I figured out how to print the log from the process in a terminal, and there are no messages when the process shuts down.
– I tried sudo sysctl debug.lowpri_throttle_enabled=0 but it doesn't make any difference.
– I have reset NVRAM and SMC. No change.
– I ran a First Aid on the backup drive. No issues.
I'm using a 2018 MacBook Pro, with Catalina 10.15 (as mentioned), and I have two external hard drives for backups (one is encrypted and one is not). They have both worked fine with Mojave, but now I have the same problem with both.
Edit: I updated to Catalina 10.15.1 and the problem persists.
Edit 2: Since I am getting so little response, let me ask some more specific questions.
How can I tell which file(s) is being copied when the backup process freezes? If I know which file, perhaps I can just delete it and the process will run.
Can I restart the backup from scratch? Perhaps if I rename the folder which holds the backup on the disk, Time-machine won't find it and start from scratch. And if I then want to access my old backups I can take back the previous folder name? Could this work? And which folder should try to I rename?