phpBB : Critical Error

Error creating new session

DEBUG MODE

SQL Error : 1062 Duplicate entry '-1' for key 2

INSERT INTO phpbb2_sessions (session_id, session_user_id, session_start, session_time, session_ip, session_page, session_logged_in, session_admin) VALUES ('f7a8937174f7f32dc2bacf51fb236df1', -1, 1548112480, 1548112480, '3457fdca', -9, 0, 0)

Line : 172
File : sessions.php