What causes Time Machine to stall during backups?

For me since fixing the firmware 'issue', the 'problem' has only come back once. I reported to Apple:

I'm sorry to say that the error returned yesterday after 37 Days, 5 hours, 3 minutes of no issues.

I then carried out:

- Quit out of Apple Books which I'd started using again earlier in the day, and had imported some ePub books

- Reformatted an external derive I use for Carbon Copy Cloner backups on some files from my NAS, as CCC reported the drive was full.

- The 'Use iPhone Widgets' on the Mac was turned off again. After the latest MacOS update it had turned the option back on.

- Emptied the rubbish bin

- Rebooted the Mac

Everything seems to be backing up normally once more.

Since that 'reset' it's now been running fine for 22 days 10 minutes. I've been sending regular status emails to Apple support, but despite that it looks like they may have closed the ticket out as links to it no longer work. I'll be chasing them next week.

Please, provide Apple with documentation of your experience via Apple Feedback. Here is the link to Apple Feedback for the Mac Mini. Feedback - Mac mini - Apple

Okay thanks I'll format the external drives and wipe the NAS partition then before going through with the procedure.

You do not need to wipe out the NAS partition. It works if you just delete the appropriate sparse bundle.

Also, make sure that you don’t turn on the Firewall again.

Does anyone know if Apple fixed this problem in the upcoming Sequoia 15.1 update?

Eh..... turn off the Firewall? Why? Are there issues with it?

I would have thought it'd be a major security issue if it was turned off?

Indeed I do!

Heck I'd not heard of it causing issues (or causing this one), is it a known issue?

Understood, hoping they do fix it in 15.2!

I quite agree. I did point them at this thread. They need to take the issue on board and resolve it.

I'm now fully restored and back to running Sequoia 15.1, so let's see if the issue reoccurs ....

Me too.

I'm just using an external drive and never(!) had any issues with it before 15.2.

I've tried everything to fix it. Nothing works.

I am waiting for 15.2. I do not dare to break out from the workin 15.0.1 I have.

I've disabled spotlight on all local drives, so I doubt it would help me.

這真的很酷 現在真正知道了

So has anyone else tried installing the OS 15.1.1 update? I did, and TM is working for two days now.