phpBB : Critical Error

Error creating new session

DEBUG MODE

SQL Error : 1062 Duplicate entry 'f6ff2dcc51191e9d6c439f096566fdba' 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 ('f6ff2dcc51191e9d6c439f096566fdba', -1, 1770373561, 1770373561, 'd849d88f', -4, 0, 0)

Line : 187
File : sessions.php