hi i wanna host on ubuntu.
but i got this error.....
how can i fix it?

2018-02-18 22:33:51 SEVERE: Errors running startup tasks:
org.h2.jdbc.JdbcSQLException: Unique index or primary key violation: "BLOCK_ID_IDX ON PUBLIC.BLOCK(ID) VALUES ( /* 17 */ 8685496526154093368 )"; SQL statement:
INSERT INTO block (id, version, timestamp, previous_block_id, total_amount, total_fee, payload_length, previous_block_hash, next_block_id, cumulative_difficulty, base_target, height, gene$

java.lang.RuntimeException: Errors running startup tasks:
org.h2.jdbc.JdbcSQLException: Unique index or primary key violation: "BLOCK_ID_IDX ON PUBLIC.BLOCK(ID) VALUES ( /* 17 */ 8685496526154093368 )"; SQL statement:
INSERT INTO block (id, version, timestamp, previous_block_id, total_amount, total_fee, payload_length, previous_block_hash, next_block_id, cumulative_difficulty, base_target, height, gene$

        at nxt.util.ThreadPool.runAll(ThreadPool.java:150)
        at nxt.util.ThreadPool.start(ThreadPool.java:74)
        at nxt.Nxt$Init.(Nxt.java:397)
        at nxt.Nxt.init(Nxt.java:329)
        at nxt.Nxt.main(Nxt.java:316)
2018-02-18 22:33:51 INFO: Shutting down...