This title is what I encountered today while I was trying to access my own svn server. After a while I figured out the problem was quite simple. Last time I set up svn, I created a wrapper script to start svnserve. The goal was to allow people to connect to my svn while not knowing the full path (and deny them the access using full path). I guess a system update rewrited the file, so no more "short url" to connect to the server, only full path.
I did again what is written there and it's fine again.