I am trying to authenticate to a mongodb database (from mongolab) using python 2.6.6 and pymongo 2.1.1 in a Debian 6.0 system.

>>> con=pymongo.Connection('xxx.mongolab.com', 31567)
>>> con.db.authenticate('abc', 'def')

Traceback (most recent call last):
File "", line 1, in
File "/usr/local/lib/python2.6/dist-packages/pymongo/database.py", line 620, in authenticate
nonce = self.command("getnonce")["nonce"]
File "/usr/local/lib/python2.6/dist-packages/pymongo/database.py", line 348, in command
result = self["$cmd"].find_one(command, **extra_opts)
File "/usr/local/lib/python2.6/dist-packages/pymongo/collection.py", line 520, in find_one
for result in self.find(spec_or_id, *args, **kwargs).limit(-1):
File "/usr/local/lib/python2.6/dist-packages/pymongo/cursor.py", line 703, in next
if len(self.__data) or self._refresh():
File "/usr/local/lib/python2.6/dist-packages/pymongo/cursor.py", line 666, in _refresh
self.__uuid_subtype))
File "/usr/local/lib/python2.6/dist-packages/pymongo/cursor.py", line 628, in __send_message
self.__tz_aware)
File "/usr/local/lib/python2.6/dist-packages/pymongo/helpers.py", line 107, in _unpack_response
result["data"] = bson.decode_all(response[20:], as_class, tz_aware)
bson.errors.InvalidBSON

Exactly the same code is working in a Windows XP system with also pymongo 2.1.1 but with python 2.7.2.