phpBB : Critical Error

Error creating new session

DEBUG MODE

SQL Error : 1062 Duplicate entry 'c278f42004f5c4106a7620f2cdef2ed6' for key 1

INSERT INTO phpbb_sessions (session_id, session_user_id, session_start, session_time, session_ip, session_page, session_logged_in, session_admin) VALUES ('c278f42004f5c4106a7620f2cdef2ed6', -1, 1413862823, 1413862823, '36d3b4af', -1, 0, 0)

Line : 187
File : sessions.php