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 ('21cc390edd37b2d142231a4b392d2564', -1, 1524205639, 1524205639, '3650082c', 33, 0, 0)

Line : 187
File : sessions.php