phpBB : Critical Error

Error creating new session

DEBUG MODE

SQL Error : 1062 Duplicate entry '-1' for key 'session_user_id'

INSERT INTO phpbb_sessions (session_id, session_user_id, session_start, session_time, session_ip, session_page, session_logged_in, session_admin) VALUES ('51fc1f68e8c1873c07954b2f0c85a377', -1, 1513438590, 1513438590, '365bab89', -1, 0, 0)

Line : 187
File : sessions.php