phpBB : Critical Error

Error creating new session

DEBUG MODE

SQL Error : 1062 Duplicate entry 'ac9a93c7ca6fdc5f0e9fccec1edd1f6a' for key 'phpbb_sessions.PRIMARY'

INSERT INTO phpbb_sessions (session_id, session_user_id, session_start, session_time, session_ip, session_page, session_logged_in, session_admin) VALUES ('ac9a93c7ca6fdc5f0e9fccec1edd1f6a', -1, 1766144383, 1766144383, 'd849d8d7', -4, 0, 0)

Line : 187
File : sessions.php