CIM is sporadically returning this error since at least 3/18:
The content type text/html of the response message does not match the content type of the binding (text/xml; charset=utf-8). If using a custom encoder, be sure that the IsContentTypeSupported method is implemented properly. The first 177 bytes of the response were: '<HTML><HEAD><TITLE>Error</TITLE></HEAD><BODY> An error occurred while processing your request.<p> Reference #179.a7ff4f17.1489957630.1e8bb331 </BODY></HTML> '.
Retrying the request (without changes) typically succeeds.
Reading the message, it appears to be some kind of reverse proxy failure on Authorize.Net's side:
Other report on Twitter: https://twitter.com/spangalang/status/843246720058245120
Support ticket is #1-405807561.
@RichardHif you could convince someone to actually look at this in a timely manner it would be appreciated