phpBB : Critical Error

Error creating new session

DEBUG MODE

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

INSERT INTO start_sessions (session_id, session_user_id, session_start, session_time, session_ip, session_page, session_logged_in) VALUES ('d8c563da034c4ddcd399186214f72f73', -1, 1425380620, 1425380620, '36d35096', 0, 0)

Line : 158
File : sessions.php