I have an html file add-offer.html containing 3 forms. I collect the data from these forms with javascript and then fetch it with fetch() to the file add-offer.php. The php file contains validation of the data, which I then try to insert into a database table. There are also two more queries that need to be executed. The data is submitted and some of it is added to the database, but I get error messages 405 and 500 and the rest of the php file is not executed.