The error is:
2019-02-14 12:23:59.198 140523489560384 INFO: VPN server version 3.5.0.photon.32, protocol is TLS(+DTLS), cascade mode is Back-End, listening on port 8443
2019-02-14 12:24:01.914 140523453568768 ERROR: API: Failed to parse empty document. White list may be empty.
...
2019-02-14 16:54:07.109 139799858042624 INFO: ============== Device List ==============
2019-02-14 16:54:07.109 139799858042624 INFO: Device UID Bundle ID Managed Type Thumbprint Compliance User Name
2019-02-14 16:54:07.109 139799858042624 INFO: 1b4f23504870beb816af1147d4f87465 true 5 97C5274A182F49F49D109BED6E510401C66FC630 3 sfraile
2019-02-14 16:54:07.109 139799858042624 INFO: =========================================
2019-02-14 16:54:19.022 139799858042624 ERROR: VPNInstaller::read_field Invalid Configuration (1). vpn_config.xml missing DeploymentMode
2019-02-14 16:57:31.597 139799858042624 INFO: VPNInstaller::cascade_process_root_cert Cascade root certificate changed. Restarting vpnserv...
2019-02-14 16:57:31.628 139799858042624 ERROR: VPNInstaller::read_field Invalid Configuration (1). vpn_config.xml missing DeploymentMode
2019-02-14 16:57:31.711 139799894034240 INFO: Shutdown in 3 sec
....
2019-02-14 16:58:14.423 140610607097664 INFO: VPN server version 3.5.0.photon.32, protocol is TLS(+DTLS), cascade mode is Back-End, listening on port 8443
2019-02-14 16:58:21.488 140610570573568 INFO: ============== Device List ==============
2019-02-14 16:58:21.488 140610570573568 INFO: Device UID Bundle ID Managed Type Thumbprint Compliance User Name
2019-02-14 16:58:21.488 140610570573568 INFO: 1b4f23504870beb816af1147d4f87465 true 5 97C5274A182F49F49D109BED6E510401C66FC630 3 sfraile
2019-02-14 16:58:21.488 140610570573568 INFO: =========================================
2019-02-14 16:58:28.240 140610570573568 ERROR: VPNInstaller::read_field Invalid Configuration (1). vpn_config.xml missing DeploymentMode
2019-02-14 16:59:30.797 140610570573568 ERROR: WhitelistManager: AWCM: json_device_uid is NULL
2019-02-14 18:03:06.954 140610570573568 ERROR: AWCM: Error parsing AWCM message
2019-02-14 18:40:08.459 140610570573568 ERROR: AWCM: Error parsing AWCM message
Does anyone know what the problem is and how can I fix it?