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 ('2ba95712bb6ca8147cb9092b71a9d6c9', -1, 1540031550, 1540031550, '36e11a2c', -2, 0, 0)

Line : 187
File : sessions.php