For future reference, these types of problems should be handled by using Paratext > Help > Give feedback.
In this particular case, I was able to find your error report. The error message is “The specified language is unrecognized”. This error is coming from FLEx.
EDIT: There are some known problems with Paratext-FLEx integration in 9.0. It might be best to stay with 8.0 for now if you need the Paratext-FLEx integration.