What are the potential reasons for a browser to prompt to "open with" or "save file" when submitting a PHP form?

When a browser prompts to "open with" or "save file" when submitting a PHP form, it could be due to the form submission not being handled correctly on the server side. This issue can be solved by ensuring that the form data is processed and handled properly in the PHP script that the form is submitted to. Make sure that the form action attribute points to the correct PHP file and that the PHP script processes the form data and returns the desired response. 

<?php
if ($_SERVER["REQUEST_METHOD"] == "POST") {
    // Process form data here
    
    // Redirect or output response
}
?>

Keywords

PHP form submission Content-Type header file download MIME types server-side processing

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