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.

rsync 3.0.3 comes with Debian lenny. In order to get a newer version I have had to use lenny-backports for this. That gets me rsync v3.0.7, which does not exhibit this bug.

(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.)