Unable to access the authentication service

Error Message

In a federated environment, ArcGIS Server must authenticate through Portal for ArcGIS to verify if users can access the Server Manager. When changes are made to a federated environment, the following error message is returned at the sign-in page:

Error:   
Unable to access the authentication service.

Cause

The federated environment was recently upgraded and a change was made to the web adaptor in some capacity (e.g. new web server, changed name).

Solution or Workaround

To resolve this issue, perform the following steps:

Warning:   
The following steps require users to unfederate and refederate the environment. Users are advised to be cautious and not rush through the federation steps to ensure further issues do not arise.

Unfederating causes content to become disassociated with the original owners. When refederated, the user that configures the federation becomes the new owner. Content must be re-associated with the correct accounts.

1. Verify if the user is using a federated environment.
2. Verify if any changes were made recently to the federated environment.
3. Verify if the web adaptor was renamed, moved, or removed.
4. If the Server Manager reaches out to the old web adaptor:
   1. Uninstall the web adaptors and reinstall/configure them to be as they were before any changes were made to the federated environment.
   2. Unfederate and refederate the environment using the new ArcGIS Server web adaptor URLs. To federate an environment, follow the steps in Federate an ArcGIS Server site with your portal.
5. Clear the browser cache.