ProtocolError when upload large file

[lazywhite]

when uploading small size file, no this problem

python-script

import xmlrpclib
import base64
import socket
socket.setdefaulttimeout(600)

sock_common = xmlrpclib.ServerProxy('http://dist.n.com:8069/xmlrpc/common', verbose=1)
oe_uid = sock_common.login('app_dist', "iposbuilder", "5FB2C84-AC31-8EEA6078E5F5")
print oe_uid

if oe_uid != False:
    print "login ok"
    sock = xmlrpclib.ServerProxy('http://dist.n.om:8069/xmlrpc/object', verbose=1)
    with open('master.ipa') as f:
        encoded = base64.b64encode(f.read())
        result = sock.execute('app_dist', oe_uid, "584-AC31-8EEA6078E5F5", 'nt.app.distribute.version', 'create', {"app_id":49,"app_version":"1.0.8","file":encoded})

socket.setdefaulttimeout(None)

error output

reply: 'HTTP/1.0 500 INTERNAL SERVER ERROR\r\n'
header: Content-Type: text/html
header: Content-Length: 291
header: Server: Werkzeug/0.8.1 Python/2.7.3
header: Date: Wed, 26 Oct 2016 08:42:50 GMT
Traceback (most recent call last):
  File "a.py", line 15, in <module>
    result = sock.execute('app_dist', oe_uid, "AC31-8EEA6078E5F5", 'nt.app.distribute.version', 'create', {"app_id":49,"app_version":"1.0.8","file":encoded})
  File "/usr/local/Cellar/python/2.7.12/Frameworks/Python.framework/Versions/2.7/lib/python2.7/xmlrpclib.py", line 1243, in __call__
    return self.__send(self.__name, args)
  File "/usr/local/Cellar/python/2.7.12/Frameworks/Python.framework/Versions/2.7/lib/python2.7/xmlrpclib.py", line 1602, in __request
    verbose=self.__verbose
  File "/usr/local/Cellar/python/2.7.12/Frameworks/Python.framework/Versions/2.7/lib/python2.7/xmlrpclib.py", line 1283, in request
    return self.single_request(host, handler, request_body, verbose)
  File "/usr/local/Cellar/python/2.7.12/Frameworks/Python.framework/Versions/2.7/lib/python2.7/xmlrpclib.py", line 1331, in single_request
    response.msg,
xmlrpclib.ProtocolError: <ProtocolError for dist.nexttao.com:8069/xmlrpc/object: 500 INTERNAL SERVER ERROR>