[EVPN VXLAN] DM traceback while restarting DM

Observed following DM traceback while restarting device-manager. DM is not pushing any config to MX

DM Traceback
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11/16/2017 12:50:38 PM [contrail-device-manager]: Next Index: esi, index:(00:11:22:33:44:55:66:77:88:11, 127)
11/16/2017 12:50:38 PM [contrail-device-manager]: Next Index: esi, index:(00:11:22:33:44:55:66:77:88:99, 126)
11/16/2017 12:50:38 PM [contrail-device-manager]: ae_id_map={'00:11:22:33:44:55:66:77:88:11': 127L, '00:11:22:33:44:55:66:77:88:99': 126L}
11/16/2017 12:50:39 PM [contrail-device-manager]: Exception: 'str' object has no attribute 'export_xml'Traceback (most recent call last):
  File "/usr/lib/python2.7/dist-packages/device_manager/db.py", line 216, in nc_handler
    self.push_config()
  File "/usr/lib/python2.7/dist-packages/device_manager/db.py", line 521, in push_config
    config_size = self.config_manager.push_conf()
  File "/usr/lib/python2.7/dist-packages/device_manager/mx_conf.py", line 827, in push_conf
    return self.send_conf()
  File "/usr/lib/python2.7/dist-packages/device_manager/juniper_conf.py", line 313, in send_conf
    return self.device_send(conf, default_operation, operation)
  File "/usr/lib/python2.7/dist-packages/device_manager/juniper_conf.py", line 131, in device_send
    config_str = self.serialize(conf)
  File "/usr/lib/python2.7/dist-packages/device_manager/juniper_conf.py", line 291, in serialize
    config.export_xml(xml_data, 1)
  File "/usr/lib/python2.7/dist-packages/device_api/juniper_common_xsd.py", line 14382, in export_xml
    self.exportChildren(outfile, level + 1, namespace_, name_, pretty_print=pretty_print)
  File "/usr/lib/python2.7/dist-packages/device_api/juniper_common_xsd.py", line 14400, in exportChildren
    self.configuration.export_xml(outfile, level, namespace_, name_='configuration', pretty_print=pretty_print)
  File "/usr/lib/python2.7/dist-packages/device_api/juniper_common_xsd.py", line 14236, in export_xml
    self.exportChildren(outfile, level + 1, namespace_, name_, pretty_print=pretty_print)
  File "/usr/lib/python2.7/dist-packages/device_api/juniper_common_xsd.py", line 14249, in exportChildren
    self.groups.export_xml(outfile, level, namespace_, name_='groups', pretty_print=pretty_print)
  File "/usr/lib/python2.7/dist-packages/device_api/juniper_common_xsd.py", line 13797, in export_xml
    self.exportChildren(outfile, level + 1, namespace_, name_, pretty_print=pretty_print)
  File "/usr/lib/python2.7/dist-packages/device_api/juniper_common_xsd.py", line 13824, in exportChildren
    self.protocols.export_xml(outfile, level, namespace_, name_='protocols', pretty_print=pretty_print)
  File "/usr/lib/python2.7/dist-packages/device_api/juniper_common_xsd.py", line 6527, in export_xml
    self.exportChildren(outfile, level + 1, namespace_, name_, pretty_print=pretty_print)
  File "/usr/lib/python2.7/dist-packages/device_api/juniper_common_xsd.py", line 6543, in exportChildren
    self.bgp.export_xml(outfile, level, namespace_, name_='bgp', pretty_print=pretty_print)
  File "/usr/lib/python2.7/dist-packages/device_api/juniper_common_xsd.py", line 6356, in export_xml
    self.exportChildren(outfile, level + 1, namespace_, name_, pretty_print=pretty_print)
  File "/usr/lib/python2.7/dist-packages/device_api/juniper_common_xsd.py", line 6371, in exportChildren
    group_.export_xml(outfile, level, namespace_, name_='group', pretty_print=pretty_print)
  File "/usr/lib/python2.7/dist-packages/device_api/juniper_common_xsd.py", line 6099, in export_xml
    self.exportChildren(outfile, level + 1, namespace_, name_, pretty_print=pretty_print)
  File "/usr/lib/python2.7/dist-packages/device_api/juniper_common_xsd.py", line 6133, in exportChildren
    self.family.export_xml(outfile, level, namespace_, name_='family', pretty_print=pretty_print)
  File "/usr/lib/python2.7/dist-packages/device_api/juniper_common_xsd.py", line 1703, in export_xml
    self.exportChildren(outfile, level + 1, namespace_, name_, pretty_print=pretty_print)
  File "/usr/lib/python2.7/dist-packages/device_api/juniper_common_xsd.py", line 1716, in exportChildren
    self.inet.export_xml(outfile, level, namespace_, name_='inet', pretty_print=pretty_print)
AttributeError: 'str' object has no attribute 'export_xml'