I need to actually check on the server, as "Please contact support about failure" is not an Composr or PHP error. It's something the web host has cooked up, directly or indirectly, and is either obscuring the true error - or possibly is a new restriction just come into place.
https://my.a2hosting.com/knowledgebase.php?_m=knowledgebase&_a=viewarticle&kbarticleid=697&nav=0,23,17