How to fix “Sorry, this file type is not permitted for security reasons” for WebP image in WordPress

If you upload a WebP image to WordPress media library, you will receive the following error:

Sorry, this file type is not permitted for security reasons

The above can be fix with a small code change. Here are all of the necessary steps:

1. Login to your Admin Panel

2. Navigate to Left Menu -> Appearance -> Theme Editor

3. Open functions.php for edit

4. At the end of the file, insert the following code:

function tishonator_webp_upload_mimes($existing_mimes) {
    $existing_mimes['webp'] = 'image/webp';
    return $existing_mimes;
}
add_filter('mime_types', 'tishonator_webp_upload_mimes');


function tishonator_webp_is_displayable($result, $path) {
    if ($result === false) {
        $displayable_image_types = array( IMAGETYPE_WEBP );
        $info = @getimagesize( $path );

        if (empty($info)) {
            $result = false;
        } elseif (!in_array($info[2], $displayable_image_types)) {
            $result = false;
        } else {
            $result = true;
        }
    }

    return $result;
}
add_filter('file_is_displayable_image', 'tishonator_webp_is_displayable', 10, 2);

5. Save changes