我使用 python、mechanize 和 flask 编写了一个小型 webapp。当我在本地运行它时，它工作得很好。
当部署在 上时pythonanywhere.com，我得到一个带有以下堆栈跟踪的“内部服务器错误”：
Traceback (most recent call last):
File "/usr/local/lib/python2.7/dist-packages/flask/app.py", line 1687, in wsgi_app
response = self.full_dispatch_request()
File "/usr/local/lib/python2.7/dist-packages/flask/app.py", line 1360, in full_dispatch_request
rv = self.handle_user_exception(e)
File "/usr/local/lib/python2.7/dist-packages/flask/app.py", line 1358, in full_dispatch_request
rv = self.dispatch_request()
File "/usr/local/lib/python2.7/dist-packages/flask/app.py", line 1344, in dispatch_request
return self.view_functions[rule.endpoint](**req.view_args)
File "/home/Lanaru/mysite/gpaviewer.py", line 34, in index
gpa = get_gpa(request.form['username'], request.form['password'])
**** File "/home/Lanaru/mysite/gpaviewer.py", line 11, in get_gpa
br.open(r'https://websiteomitted.com/')
File "/usr/local/lib/python2.7/dist-packages/mechanize/_mechanize.py", line 203, in open
return self._mech_open(url, data, timeout=timeout)
File "/usr/local/lib/python2.7/dist-packages/mechanize/_mechanize.py", line 230, in _mech_open
response = UserAgentBase.open(self, request, data)
File "/usr/local/lib/python2.7/dist-packages/mechanize/_opener.py", line 193, in open
response = urlopen(self, req, data)
File "/usr/local/lib/python2.7/dist-packages/mechanize/_urllib2_fork.py", line 344, in _open
'_open', req)
File "/usr/local/lib/python2.7/dist-packages/mechanize/_urllib2_fork.py", line 332, in _call_chain
result = func(*args)
File "/usr/local/lib/python2.7/dist-packages/mechanize/_urllib2_fork.py", line 1170, in https_open
return self.do_open(conn_factory, req)
File "/usr/local/lib/python2.7/dist-packages/mechanize/_urllib2_fork.py", line 1118, in do_open
raise URLError(err)
URLError: <urlopen error Tunnel connection failed: 403 Forbidden>
为什么我会收到此 urlopen 错误，我该如何解决？