Traccar server stops working after midnight

Traccar server 3.13, system Debian, Mysql.

Every day stops working after midnight

ok...ok...

2017-07-21 22:28:05  INFO: [47F662CE] connected
2017-07-21 22:28:23 DEBUG: [47F662CE: 5001 < 198.11.121.50] HEX: 474554202f20485454502f312e310d0a486f73743a203130392e39352e32372e36360d0a0d0a
2017-07-21 22:28:35  INFO: [47F662CE] disconnected
2017-07-21 22:41:57  INFO: [E4B51C12] connected
2017-07-21 22:42:15 DEBUG: [E4B51C12: 5001 < 198.11.121.50] HEX: 474554202f20485454502f312e310d0a486f73743a203130392e39352e32372e36360d0a0d0a
2017-07-21 22:42:28  INFO: [E4B51C12] disconnected
2017-07-21 23:53:52  INFO: [34658388] connected
2017-07-21 23:54:10 DEBUG: [34658388: 5001 < 198.11.121.50] HEX: 474554202f20485454502f312e310d0a486f73743a203130392e39352e32372e36360d0a0d0a
2017-07-21 23:54:26  INFO: [34658388] disconnected

after midnight error:

2017-07-22 00:11:01  INFO: [DBE14570] connected
2017-07-22 00:11:19 DEBUG: [DBE14570: 5001 < 27.54.181.10] HEX: 474554202f20485454502f312e310d0a486f73743a203130392e39352e32372e36360d0a0d0a
2017-07-22 00:11:20  WARN: [DBE14570] error - scheme - NullPointerException (... < StatisticsManager:73 < *:112 < BaseProtocolDecoder:182 < ExtendedObjectDecoder:59 < ...)
2017-07-22 00:11:20  INFO: [DBE14570] disconnected
2017-07-22 00:11:20  WARN: [DBE14570] error - scheme - NullPointerException (... < StatisticsManager:73 < *:112 < BaseProtocolDecoder:182 < ExtendedObjectDecoder:59 < ...)
2017-07-22 00:11:20  WARN: [DBE14570] error - scheme - NullPointerException (... < StatisticsManager:73 < *:112 < BaseProtocolDecoder:182 < ExtendedObjectDecoder:59 < ...)
2017-07-22 00:56:54  INFO: [B75933BF] connected
2017-07-22 00:57:12 DEBUG: [B75933BF: 5001 < 198.11.121.50] HEX: 474554202f20485454502f312e310d0a486f73743a203130392e39352e32372e36360d0a0d0a
2017-07-22 00:57:12  WARN: [B75933BF] error - scheme - NullPointerException (... < StatisticsManager:73 < *:112 < BaseProtocolDecoder:182 < ExtendedObjectDecoder:59 < ...)
2017-07-22 00:57:12  INFO: [B75933BF] disconnected

restart traccar
ok...ok...

2017-07-22 23:52:14  INFO: [EAACF9C7] connected
2017-07-22 23:52:33 DEBUG: [EAACF9C7: 5001 < 198.11.121.50] HEX: 474554202f20485454502f312e310d0a486f73743a203130392e39352e32372e36360d0a0d0a
2017-07-22 23:52:45  INFO: [EAACF9C7] disconnected
2017-07-22 23:54:58  INFO: [AEB97606] connected
2017-07-22 23:55:16 DEBUG: [AEB97606: 5001 < 198.11.121.50] HEX: 474554202f20485454502f312e310d0a486f73743a203130392e39352e32372e36360d0a0d0a
2017-07-22 23:55:31  INFO: [AEB97606] disconnected
2017-07-22 23:58:39  INFO: [C2307B96] connected
2017-07-22 23:58:57 DEBUG: [C2307B96: 5001 < 38.107.90.89] HEX: 474554202f20485454502f312e310d0a486f73743a203130392e39352e32372e36360d0a0d0a
2017-07-22 23:59:12  INFO: [C2307B96] disconnected

after midnight error:

2017-07-23 00:10:38  INFO: [11F94228] connected
2017-07-23 00:10:56 DEBUG: [11F94228: 5001 < 198.11.121.50] HEX: 474554202f20485454502f312e310d0a486f73743a203130392e39352e32372e36360d0a0d0a
2017-07-23 00:10:56  WARN: [11F94228] error - scheme - NullPointerException (... < StatisticsManager:73 < *:112 < BaseProtocolDecoder:182 < ExtendedObjectDecoder:59 < ...)
2017-07-23 00:10:56  INFO: [11F94228] disconnected
2017-07-23 00:10:56  WARN: [11F94228] error - scheme - NullPointerException (... < StatisticsManager:73 < *:112 < BaseProtocolDecoder:182 < ExtendedObjectDecoder:59 < ...)
2017-07-23 00:10:56  WARN: [11F94228] error - scheme - NullPointerException (... < StatisticsManager:73 < *:112 < BaseProtocolDecoder:182 < ExtendedObjectDecoder:59 < ...)

You have invalid URL as "server.statistics" config parameter. Next time you should probably mention what modifications you did to the config. If you don't say anything the assumption is that you are using official release without any modifications whatsoever.