Failed to create snapshot: Can't find bundle for base name messages.UIDesignerBundle, locale en_US

Attempted to create a snapshot based off of an existing GUI project I had, but it didn't work for some reason. 

I got this error after going to File>New>Swing UI Designer>Snapshot:

Failed to create snapshot: Can't find bundle for base name messages.UIDesignerBundle, locale en_US

One thing I noticed is that it wasn't aware that my program was already running and made me run a 2nd instance of it as well. Any help would be appreciated.