Add support for WOFF and WOFF2 file uploads in WordPress

functions.php

<?php

// The following code goes in your functions.php file of a Child Theme

function custom_font_mime_types($mimes = array()) {
  $mimes['woff'] = 'application/x-font-woff';
  $mimes['woff2'] = 'application/x-font-woff2';
  // Depending on your server setup, you may need to use these instead:
  //$mimes['woff'] = 'font/woff';
  //$mimes['woff2'] = 'font/woff2';
  return $mimes;
}
add_filter('upload_mimes', 'custom_font_mime_types');