"Error initializing refactoring" when renaming instance variable

[flbulgarelli]

I tried to rename energia and I got error "Error initializing refactoring. null. See log for details"

object pepita {
    var energia
    method estaViva() {
        return energia == 4;
    }
}

[flbulgarelli]

Update: it doesn't occur always. It is not occurring right after Eclipse start.

[fdodino]

I could reproduce it, when you start Eclipse it shows a warning message: "Missconfigured language.New reference text has invalid syntax"

There is no log on "Error log" tab. I once fixed it but wasn't sure about their implicancies. I touched some scoped import.