Suds
client is used by vatnumber
module to query VIES system for VAT ID numbers. The problem was it was making an error (exception that NoneType does not have str method). This error was shown only with django (with possibly django-debug-toolbar enabled). As we can read here http://stackoverflow.com/questions/9664705/django-and-suds-nonetype-object-has-no-attribute-str-in-suds this is a bug in Suds
that is caused by some logging problem. In console this bug fails silently, but when called from django make an Exception.
As stackoverflow answers, the solution is to use fixed version of Suds
that unfortunately is not in PyPi. Working suds version can be clone from: https://github.com/cypreess/suds-htj.git
Version: 0.4.1-htj is reported to be working.