phpBB : Critical Error

Error creating new session

DEBUG MODE

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

INSERT INTO phpbb_sessions (session_id, session_user_id, session_start, session_time, session_ip, session_page, session_logged_in, session_admin) VALUES ('969e7649c69196bb5fcc61c251b3cbb0', -1, 1563412564, 1563412564, '365c94a5', -4, 0, 0)

Line : 187
File : sessions.php