phpBB : Critical Error

Error creating new session

DEBUG MODE

SQL Error : 1062 Duplicate entry '1a97649caf09f4560f7ba138e51732cf' 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 ('1a97649caf09f4560f7ba138e51732cf', -1, 1419136983, 1419136983, '36504598', -1, 0, 0)

Line : 187
File : sessions.php