Backup fails because of a file that is not even into the source directory to be backed up sync warning: some files vanished before they could be transferred (code 24)

[bjce]

I am trying to backup the /User/user01/Library using rsync (via the linux-timemachine wrapper https://github.com/cytopia/linux-timemachine) to an external hard drive Volumes/name_of_backup logged in as user01. During the backup I get the following error message

rsync warning: some files vanished before they could be transferred (code 24) at /System/Volumes/Data/SWE/macOS/BuildRoots/220e8a1b79/Library/Caches/com.apple.xbs/Sources/rsync/rsync-55/rsync/main.c(996) [sender=2.6.9]

What I don't understand is that the file /System/Volumes/Data/SWE/macOS/BuildRoots/220e8a1b79/Library/Caches/com.apple.xbs/Sources/rsync/rsync-55/rsync/main.c is not even located in the directory that I am trying to backup (namely /User/user01/Library). So why does this error appears? And most importantly how can I get rid of the problem?

[Hofundur]

It is not an issue with timemachine, even not in rsync. It happenes when rsync tries synchro file that disappear after list, offen with tmp or cache files like in this case. This is not an error, you can ignore this warning.
Why this files was tried to rsync that file? Probably you have soft links to other directories. You can ignore liked resources, but you should know what are you doing before using this options.