phpBB : Critical Error

Error creating new session

DEBUG MODE

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

INSERT INTO r2ok_sessions (session_id, session_user_id, session_start, session_time, session_ip, session_page, session_logged_in, session_admin) VALUES ('7b61d5c8ca8ca949b93ea67b51c6700a', -1, 1524206686, 1524206686, '3650082c', 32, 0, 0)

Line : 187
File : sessions.php