phpBB : Critical Error

Error creating new session

DEBUG MODE

SQL Error : 1062 Duplicate entry '4a7bb27fee0965a2f29f35a4e902a4fa' for key 1

INSERT INTO phpbb_sessions (session_id, session_user_id, session_start, session_time, session_ip, session_page, session_logged_in, session_admin) VALUES ('4a7bb27fee0965a2f29f35a4e902a4fa', -1, 1398076516, 1398076516, '36f30d1e', 0, 0, 0)

Line : 187
File : sessions.php