I keep some directories synchronized between my notebook and desktop with rsync. After upgrading my desktop to Mac OS 15.4.1, I started getting errors:

[sjg@BigThud 2025-04-21 13:01:05] ~/Documents/Backup
$ rsync -auP . sjg@10.3.2.xx:Documents/Backup
(sjg@10.3.2.xx) Password:
rsync: failed to set times on "/Users/sjg/Documents/Backup/Whatever": Operation not permitted (1)

Interestingly, ssh also showed an error:

[sjg@BigThud 2025-04-21 13:04:29] ~/Documents/Backup
$ ssh sjg@10.3.2.xx "ls /Users/sjg/Documents/Backup/Whatever"
(sjg@10.3.2.xx) Password:
ls: /Users/sjg/Documents/Backup/Whatever: Operation not permitted

On the desktop, I look again at Documents/Backup/Whatever, and the permissions are fine. What gives?

To make a long story short, something in the latest update on the desktop changed sshd‘s full disk access permission. Looking at System Preferences > Privacy & Security > Full Disk Access, sshd-keygen-wrapper was checked, so it should have been enabled. I tried toggling that, but it didn’t help.

Apparently, the sshd-keygen-wrapper was pointing at an old version or something? I had to go into System Preferences > General > Sharing and turn Remote Login off then on again, then go into System Preferences > Privacy & Security > Full Disk Access and re-enable sshd-keygen-wrapper.

Et voilà, I could ssh and rsync again!