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 ('2011a1233211c57701721d011e1a5dc1', -1, 1713484719, 1713484719, '12760907', -2, 0, 0)

Line : 187
File : sessions.php