[[!comment format=mdwn
 username="joey"
 subject="""comment 1"""
 date="2015-08-19T16:12:12Z"
 content="""
From the rsync man page that the error directs you to:

> rsync occasionally produces error messages that may seem a little cryp‐
> tic. The one that seems to cause the most confusion is  "protocol  ver‐
> sion mismatch -- is your shell clean?".

> This  message is usually caused by your startup scripts or remote shell
> facility producing unwanted garbage on the stream that rsync  is  using
> for  its  transport.  The  way  to diagnose this problem is to run your
> remote shell like this:

>        ssh remotehost /bin/true > out.dat


> then look at out.dat. If everything is working correctly  then  out.dat
> should  be  a zero length file. If you are getting the above error from
> rsync then you will probably find that out.dat contains  some  text  or
> data.  Look  at  the contents and try to work out what is producing it.
> The most common cause is incorrectly configured shell  startup  scripts
> (such  as  .cshrc  or  .profile)  that  contain  output  statements for
> non-interactive logins.

"""]]