phpBB : Critical Error

Error creating new session

DEBUG MODE

SQL Error : 1062 Duplicate entry '4421f70cfb8e8e82fa26cef0657bea4d' for key 'PRIMARY'

INSERT INTO phpbb_sessions (session_id, session_user_id, session_start, session_time, session_ip, session_page, session_logged_in, session_admin) VALUES ('4421f70cfb8e8e82fa26cef0657bea4d', -1, 1398082518, 1398082518, '36f31781', -1, 0, 0)

Line : 187
File : sessions.php