ArcGIS Enterprise error AADSTS50011: The reply URL specified in the request does not match the reply URLs configured for the application

Error Message

After upgrading ArcGIS Enterprise, attempting to log in to Microsoft Azure using Security Assertion Markup Language (SAML) returns the following error:

Error:   
AADSTS50011: The reply URL '<Server FQDN URL>' specified in the request does not match the reply URLs configured for the application '<GUID>'. Make sure the reply URL sent in the request matches one added to your application in the Azure portal. Navigate to https://aka.ms/urlMismatchError to learn more about how to fix this.

Cause

The WebContextURL property is removed after upgrading ArcGIS Enterprise. Without the WebContextURL parameter, the portal's SAML metadata is updated to use the fully qualified domain name (FQDN) machine URL, which does not match the metadata in the Microsoft Azure portal.

Solution or Workaround

Set the WebContextURL property in the ArcGIS Portal Administrator Directory and restart the Microsoft Azure portal service. Refer to Portal for ArcGIS: Configure a portal to use a reverse proxy or load balancer for further instructions.