phpBB : Critical Error

Error creating new session

DEBUG MODE

SQL Error : 1062 Duplicate entry '18121f9a9c0bbe3113b3417629195e1b' for key 1

INSERT INTO phpbb2_sessions (session_id, session_user_id, session_start, session_time, session_ip, session_page, session_logged_in, session_admin) VALUES ('18121f9a9c0bbe3113b3417629195e1b', -1, 1495466888, 1495466888, '3651683d', 19, 0, 0)

Line : 187
File : sessions.php