phpBB : Critical Error

Error creating new session

DEBUG MODE

SQL Error : 1062 Duplicate entry '778e6a8157f281cecd5f18b9a2e6211d' 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 ('778e6a8157f281cecd5f18b9a2e6211d', -1, 1768118255, 1768118255, 'd849d8a2', -4, 0, 0)

Line : 187
File : sessions.php