JS POST update data taxonomies

In this case you issue your ID while you have to look for the “name” or “value”.

if( isset( $_POST['user_activities-'.$useractivitie->slug] ) )

Change to:

if( isset( $_POST['user_activities'][$useractivitie] ) )

Hata!: SQLSTATE[HY000] [1045] Access denied for user 'divattrend_liink'@'localhost' (using password: YES)