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 ('62cec6eeb3ec8c77268d750bc87658f6', -1, 1492948018, 1492948018, '365ca709', 26, 0, 0)

Line : 172
File : sessions.php