phpBB : Critical Error

Error creating new session

DEBUG MODE

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

INSERT INTO forum_sessions (session_id, session_user_id, session_start, session_time, session_ip, session_page, session_logged_in, session_admin) VALUES ('a5db31fd5b9b76013b3a33cf2a1b6aa6', -1, 1427681764, 1427681764, '36c59fc1', 1, 0, 0)

Line : 187
File : sessions.php