phpBB : Critical Error

Error creating new session

DEBUG MODE

SQL Error : 1062 Duplicate entry 'c2ac8d0c1e18df8afd447a05a1f4f1df' 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 ('c2ac8d0c1e18df8afd447a05a1f4f1df', -1, 1770203945, 1770203945, 'd849d805', 4, 0, 0)

Line : 187
File : sessions.php