phpBB : Critical Error

Error creating new session

DEBUG MODE

SQL Error : 1062 Duplicate entry '797f7f04e3d3229be314bc94ae08534f' 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 ('797f7f04e3d3229be314bc94ae08534f', -1, 1414755381, 1414755381, 'adf536d4', 11, 0, 0)

Line : 245
File : sessions.php