phpBB : Critical Error

Error creating new session

DEBUG MODE

SQL Error : 1062 Duplicate entry '-1' for key 2

INSERT INTO zagataphpbb_sessions (session_id, session_user_id, session_start, session_time, session_ip, session_page, session_logged_in, session_admin) VALUES ('981a7f7daf2f6ca6f32179d034fc4184', -1, 1498646168, 1498646168, '36a16927', 8, 0, 0)

Line : 187
File : sessions.php