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 ('c0f4b27767245eacd23295b4c7e532ed', -1, 1539942470, 1539942470, 'c0a865fd', -1, 0, 0)

Line : 187
File : sessions.php