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 ('27664e5c44b0ea7b0e84c670406a9e81', -1, 1539942586, 1539942586, 'c0a865fd', -1, 0, 0)

Line : 187
File : sessions.php