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 ('f34fc106813b7eb4067b8e84842aa724', -1, 1542044479, 1542044479, '36c46e55', 4, 0, 0)

Line : 187
File : sessions.php