Am surprised you are trying to extract parts rather than using linked parts, but I realize some circumstances mat require at least certain parts to be extracted.

Are you using the base F2014 program or 2014.5?

At what part of the extraction process do you see the error message? The extracted part should be same .musx format as your original file. So something funny seems to be happening.

Have you tried using the "Submit a request" link above to send the Finale document to MakeMusic Support for analysis?