Following up on a change of default URL for a WebAppllication on SharePoint 2013, the site did not respond correctly.
Finding the a
Unexpected SPAudienceValidator Audience URI '[OLDURL]' is not valid for context
in the ULS led me to this blog post https://gavinmckay.wordpress.com/2014/11/28/fixing-sharepoint-2013-unexpected-spaudiencevalidator-audience-uri-is-not-valid-for-context/
Indeed a caching issue, in my case a flush of the DNS and a reset of the web server was sufficient.