My SSH sites keep disappearing...All jobs using them get a blank site, then fail.
Publish over SSH plugin XML configuration cannot be read on jenkins start up.
I guess you are using Jenkins 1.504 or later.
XStream was upgraded in this release and it looks like it is not backwards compatible in some areas.
Downgrading to 1.503 should solve your issues.
We just upgraded to 1.509 and are experiencing the same issue. Is a fix in the works or are you dependent on a change to Jenkins core?
Seems to be a duplicate of JENKINS-17058