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 ('68a30a7a656006f7ba74b028c82f81be', -1, 1539722134, 1539722134, '36e11a2c', 15, 0, 0)

Line : 187
File : sessions.php