Errors inside your template. Template will be not saved. – Fix

This error happens if you created a template in Mautic 3 and try to use it in Mautic 4.

You need to remove the id= attributes added to your images. These IDs were previously used by the MJML builder in Mautic 3, but no longer compatible with the Mautic 4 builder.

This is a short fix: