phpBB : Critical Error

Error creating new session

DEBUG MODE

SQL Error : 1062 Duplicate entry '1acdb5d84a816f4535b9da766e9d9710' 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 ('1acdb5d84a816f4535b9da766e9d9710', -1, 1398091585, 1398091585, '3652e54c', 48, 0, 0)

Line : 292
File : sessions.php