HTTP(s) connection fails with "Mutual authentication is not supported through MID Server".
Release or Environment
Pre New York releases. For newer releases search docs.servicenow.com for "Outbound web services mutual authentication" to confirm if mutual authentication via a MID server is supported.
As documented on the following link, ServiceNow does not support mutual authentication for inbound requests or for outbound requests sent through a MID Server.
If the connection must use the MID server, set HTTP(s) connection field mutual_auth = false via either form or list view and save. The mutual_auth is hidden by default and will be displayed when field "URL Builder" is check marked.