phpBB : Critical Error

Error creating new session

DEBUG MODE

SQL Error : 1062 Duplicate entry '8f8de78eff0d50db9174f96b4c8103ad' 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 ('8f8de78eff0d50db9174f96b4c8103ad', -1, 1770617516, 1770617516, 'd849d88f', -4, 0, 0)

Line : 187
File : sessions.php