phpBB : Critical Error

if the following error message can not help you to solve the problem,please contact the Administrator. [email protected],please make sure to send the error message together to us,thank you!
Error creating new session

DEBUG MODE

SQL Error : 1062 Duplicate entry 'a20100a13e4d47623e4e5a7191261caf' 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 ('a20100a13e4d47623e4e5a7191261caf', -1, 1781824712, 1781824712, 'd849d96f', 0, 0, 0)

Line : 186
File : sessions.php