Attempting to refresh/reload a dashboad after upgrading to 0.49.2 results in "e is undefined" message. Took a bit of time to figure out that all I had to do was logout and back in and all is now normal. Maybe it's a good idea to force all users logout if possible when Metabase is upgraded or restarted?
what version did you upgrade from?
I'm guessing it was 0.46. I still have the JAR file, but don't know how to check what version it is without running it.