2017-11-16 23:04:52 WARN: Data truncation: Incorrect datetime value: '1969-12-31 21:00:00' for column 'fixtime' at row 1 - MysqlDataTruncation (... < QueryBuilder:477 < DataManager:327 < DefaultDataHandler:27 < ...)
Looks like you are using MySQL and you didn't allow zero timestamps.
It's not a critical issue. Why do you want to solve it?