How to allow files with extensions that aren’t supported by the WordPress default, to be uploaded?

There are certain file extensions that are not support by the WordPress in default. Now, using the ‘File Upload’ filed in the Everest Forms Pro, you can upload any file extensions to your form. You just have to follow the steps below to achieve this freedom of uploading.

• If not set true, go to wp-config.php[using FTP] and set the constant ALLOW_UNFILTERED_UPLOADS as true. It should be:

define( 'ALLOW_UNFILTERED_UPLOADS', true );

• Add the file extension in the ‘Allowed File Extensions’ option. You can find in the field options for ‘File Upload’ field. For example, we have taken a ‘heic’ file for reference.
  

• Then, go to the functions.php file of your current theme and add the following codes.
  

add_action( 'wp_footer', 'twentytwentyone_add_ie_class' );

function add_evf_support( $mimes ) {
$mimes['heic'] = 'application/heic';
return $mimes;
}
add_filter( 'upload_mimes', 'add_evf_support' );

For multiple extensions, please check the screenshot below and add accordingly.