Can't get my Mac to backup my iPhone

Tom Wolsky wrote:

The phone didn't mount in Safe Boot at all

Well, still preparing. I'm thinking this isn't working.

Yes this is an oddity.

Old backups are typically over written unless they are archived.

From your Finder you said you deleted old iPhone backups...(?)

iPhone Backups—

Finder>Go>Go To Library,  copy & paste:

~/Library/Application Support/MobileSync/Backup

here is an older example:

from Finder—

Tom Wolsky wrote:

It stopped backing up. If I try to backup with Backup Now, I get a message that my backup is corrupted and to delete it. I deleted the backup, and the archives. The Mac now shows that it's never backed up the phone.

https://discussions.apple.com/content/attachment/320045e3-ea35-4901-a6e8-87a27a753bcf

When I try to backup again I still get the error.

https://discussions.apple.com/content/attachment/5c5fb06d-fb57-4a28-9ff0-d8de3496694f

This is on an M1 MBP with 12.4.

Any suggestions would be really appreciated.

Thanks very much.

try a safeboot

SafeBoot How to use safe mode on your Mac - Apple Support

Takes a bit longer to get to the login screen, does a quick disk repair before it fully boots up, and certain system caches get cleared and rebuilt, including dynamic loader cache, etc.

Login and test your backup.

Reboot as normal and test. Caches get rebuilt automatically.

Tom Wolsky wrote:

Thank you very much Leroy.

There was indeed a lot of folders, most them empty, inside Backup. I dumped everything in Mobile Sync, connected the phone, and was able to get a complete backup.

Stuck on trying to sync now. It's preparing for that, but at least there's a backup.

Thank you again for the great help.

I do not know about the "automatic" sync option time frame, I do not use it instead I do "manual" .

I did want to add that in the Finder interface for your iPhone when clicking: manage...

holding the Control key when selecting a backup there, reveals the options: I like to keep one archive that does not get over written.

For what it's worth, I have found iMazing to be a reliable and helpful app for backing up and otherwise maintaining my iPhones. It makes its own backups (independent of Finder-based backups) and I like the ability to have an alternate backup method.

I initially bought it because my iMac (Catalina 10.15.17) refuses to sync my calendar events older than 30 days. I could not find any way around the problem. iMazing was able to back up (and export) everything, even allowing filters on dates, etc.

Have you tried using the Finder to backup your iPhone to your Mac?

It's like it used to be with iTunes but it's part of the Finder now.

Did you try backing up while in Safe Mode as leroy douglas suggested?