Error Setting up for audio extraction

Thank you very much for the answer. The main issue was a part of unreferenced media that was "left" by the editor in one of the FCPX multicam timelines. They just sent me the audio files and the fcpxml. As there are further audio files missing, I will receive the entire FCPX project (95 min timeline) so I can clean it by myself.

Please zip and attach your FCPXML here.

What version of OS X are you running?
Do you have any "Media Locations" configured in the X2Pro Preferences?
If you do not have any "Media Locations" configured then take a look at this and see why X2Pro may need them on your system.
x2pro.net/sandboxing.html

When I try to convert an XML from FCPX I get the following error message and need immediate help:

Writing AAF file
Adding assets to AAF file
Adding essence for asset [Auto-detected stereo] to AAF file
Opening audio extractor for portion 0 of asset [Auto-detected stereo]
Failed to initialise audio extractor with default bit depth of 24
Error Setting up for audio extraction (The requested URL was not found on this server.)

Suggestion: Does this movie contain an unsupported audio format ?

No AAF file has been generated.
X2Pro Audio Convert 3.0.13