None of this worked for me but I was able to solve the problem the old school way. I went into the sharing system preferences and into options. I unchecked everything. There was a user for sharing privileges in the list that was called undefined (or something like that: this also was a new mac that had been migrated from the old one). I removed that user in the privileges list. I had tried before but with the check marks enabled, it would not let me. This time is did. (Presumably, it was in use.) It wasn't in the apple users list so no need to worry about that. I then went back to options and checked everything back on. Presto! The sharing was fixed. I hope that helps.