Got error when setuping anki server on Ubuntu

[barrychi]

Exception happened during processing of request from ('192.168.31.225', 33030)
Traceback (most recent call last):
File "/usr/local/lib/python2.7/dist-packages/Paste-3.0.8-py2.7.egg/paste/httpserver.py", line 1090, in process_request_in_thread
self.finish_request(request, client_address)
File "/usr/lib/python2.7/SocketServer.py", line 334, in finish_request
self.RequestHandlerClass(request, client_address, self)
File "/usr/lib/python2.7/SocketServer.py", line 649, in init
self.handle()
File "/usr/local/lib/python2.7/dist-packages/Paste-3.0.8-py2.7.egg/paste/httpserver.py", line 459, in handle
BaseHTTPRequestHandler.handle(self)
File "/usr/lib/python2.7/BaseHTTPServer.py", line 340, in handle
self.handle_one_request()
File "/usr/local/lib/python2.7/dist-packages/Paste-3.0.8-py2.7.egg/paste/httpserver.py", line 454, in handle_one_request
self.wsgi_execute()
File "/usr/local/lib/python2.7/dist-packages/Paste-3.0.8-py2.7.egg/paste/httpserver.py", line 304, in wsgi_execute
self.wsgi_start_response)
File "/usr/local/lib/python2.7/dist-packages/Paste-3.0.8-py2.7.egg/paste/translogger.py", line 69, in call
return self.application(environ, replacement_start_response)
File "/usr/local/lib/python2.7/dist-packages/Paste-3.0.8-py2.7.egg/paste/urlmap.py", line 216, in call
return app(environ, start_response)
File "build/bdist.linux-x86_64/egg/webob/dec.py", line 129, in call
resp = self.call_func(req, *args, **kw)
File "build/bdist.linux-x86_64/egg/webob/dec.py", line 193, in call_func
return self.func(req, *args, **kwargs)
File "/home/barry/Anki-Server/AnkiServer-2.0.6/AnkiServer/apps/sync_app.py", line 582, in call
result = self._execute_handler_method_in_thread(url, data, session)
File "/home/barry/Anki-Server/AnkiServer-2.0.6/AnkiServer/apps/sync_app.py", line 660, in _execute_handler_method_in_thread
result = thread.execute(run_func)
File "/home/barry/Anki-Server/AnkiServer-2.0.6/AnkiServer/threading.py", line 76, in execute
raise ret
AttributeError: 'MediaManager' object has no attribute 'lastUsn'

ubuntu 14 LTS
sync on ankidroid