rsync error: failed to set times on “/foo/bar”: Op

Question

I'm getting a confusing error from rsync and the initial things I'm finding from web searches (as well as all the usual chmod'ing) are not solving it:

rsync: failed to set times on "/foo/bar": Operation not permitted (1)
rsync error: some files could not be transferred (code 23) 
  at /SourceCache/rsync/rsync-35.2/rsync/main.c(992) [sender=2.6.9]

It seems to be working despite that error, but it would be nice to get rid of that.

Answer 1

The problem in my case was that the "receiver mountpoint" was incorrectly mounted. It was in read-only mode (for some extrange reason). It looked like rsync was copying the files, but it was not. I checked my fstab file and changed mount options to default, re-mount file system and execute rsync again. All fine then.

Answer 2

The issue is probably due to /foo/bar not being owned by the writing process on a remote darwin (OS X) system. A solution to the issue is to set adequate owner on the remote site.

Since this answer has been voted, and therefore has been hopefully useful to someone, I'm extending it to make it clearer.

The reason why this happens is that rsync is probably trying to set an arbitrary modification time (mtime) when copying files.

In order to do this darwin's system utime() function requires that the writing process effective uid is either the same as the file uid or super user's one, see opengroup utime's page. Check this discussion on rsync mailing list as reference.