Today one of my rsync backups began failing with:
inflate (token) returned -5 rsync error: error in rsync protocol data stream (code 12) at token.c(604) [receiver=3.0.3] rsync: writefd_unbuffered failed to write 373 bytes [generator]: Broken pipe (32) rsync error: error in rsync protocol data stream (code 12) at io.c(1544) [generator=3.0.3]
It was repeatable when trying to transfer the same file (a large gzipped SQL dump file).
It turned out to be a bug in that version of rsync.
(Yes, I am aware that squeeze has been released and this host should be upgraded to that. There is security support for lenny until at least February 2012.)