I have had this problem many times. During development when something went wrong with my application, all I could get after the Internal server error would be JBO:XXXX error code with numerous question marks instead of the actual error message.
Some people advised me to change the preferred language/locale of my WEB browser and make it English, so as to force the display of error messages in this language, but that didn't work either.
Today I found a remedy. Open the project properties Go to Run/Debug click edit and add
-Duser.language=en -Duser.country=US in the java command line options, like I show you in the following pciture
... and that does it.