Error upon calling /register on recaptchaplugin

[T. N.R]

If anyone tries to register itself i get this error:

2011-12-16 09:10:47,082 Trac[main] ERROR: Internal Server Error: 
Traceback (most recent call last):
  File "build/bdist.linux-x86_64/egg/trac/web/main.py", line 511, in _dispatch_request
    dispatcher.dispatch(req)
  File "build/bdist.linux-x86_64/egg/trac/web/main.py", line 237, in dispatch
    resp = chosen_handler.process_request(req)
  File "build/bdist.linux-x86_64/egg/recaptcharegister/web_ui.py", line 40, in process_request
    ret = super(RecaptchaRegistrationModule, self).process_request(req)
  File "build/bdist.linux-x86_64/egg/acct_mgr/web_ui.py", line 456, in process_request
    _create_user(req, self.env)
  File "build/bdist.linux-x86_64/egg/acct_mgr/web_ui.py", line 48, in _create_user
    req.args.get('username').strip())
AttributeError: 'NoneType' object has no attribute 'strip'

any ideas why?

[Steffen Hoffmann]

Replying to get@winsucks.org:

If anyone tries to register itself i get this error: ... any ideas why?

Yes, please search existing tickets for identical, similar and related issues first.

This is a duplicate of #9524.