Connector/python execute many NoneType

Connector/python execute many NoneType

I have a little problem with Connector/python executing insert query.
I have function to insert data into database. Argument data is list of
tuples: [(2652884, 'http://www.example.com/', '5.0.5.239', 1), ..... ]
def insert_url(self, data):
query = "INSERT INTO `sp_urls` (`parent_id`, `url`, `version`, `hits`)
VALUES (%d, %s, %s, %d) ON DUPLICATE KEY UPDATE url=url"
try:
cursor = self.__cnx.cursor()
cursor.executemany(query, data)
except (mysql.connector.errors.IntegrityError) as err:
print("Query syntax error:", err, file=sys.stderr)
except (mysql.connector.errors.ProgrammingError) as err:
print("Programming err:{0}".format(err))
finally:
cursor.close()
The query itself works, in self.__cnx is initialized connection. Here's
the traceback:
File "sdi/database/DbValidator.py", line 91, in process_records
self.__driver.insert_url(urldata)
File "/home/david/workspace/stickydi/sdi/database/MySQLDriver.py", line
87, in insert_url
cursor.executemany(query, data)
File "/usr/lib/python3/dist-packages/mysql/connector/cursor.py", line 492,
in executemany
return self._batch_insert(operation,seq_params)
File "/usr/lib/python3/dist-packages/mysql/connector/cursor.py", line 428,
in _batch_insert
fmt = m.group(1).encode(self._connection.charset)
AttributeError: 'NoneType' object has no attribute 'group'
I have one very similar method, and it works OK, I just can't see, why
does executemany( ) goes wrong.
Thank you for your advice.