I cannot save the incoming data of communication to the database

I partially divided the asp mvc net8 html component into communication parts in the form of createmessage. The default index directory is not saved in any way.

[Messagecontroller](https://i.sstatic.net/eAdEnZFv.png)
[/views/message/createmessage.cshtml](https://i.sstatic.net/lGYdQQq9.png)
[main.js](https://i.sstatic.net/ClTZBgrk.png)
[default/index](https://i.sstatic.net/pwlXpQfg.png)
[solution explorer](https://i.sstatic.net/pBCCttvf.png)
[sendEmail.php errors](https://i.sstatic.net/Aj47Rz8J.png)

I changed the path of sendemail.php in the javascript file and tried createmessage, but it didn’t work.
When I open the page from the createmessage view, the theme does not appear, but the boxes appear. When I fill the boxes with information and send the data, the data is stored in my database. This storage process is not in the default index.