How did you get to r449 if you're running stable?
You can go into Edit Settings, then change the development branch from 'stable' to 'experimental', after which time experimental updates will be available to you
I don't know, but that's the stable version number that was available for update. I just updated to the experimental version to get rid of the error messages. Is it possible to revert to the last stable version, or am I stuck with experimental now?