ArcGIS Enterprise portal: The server at <Portal_URL> returned an error. Could not decrypt token. Token may not be valid

Error Message

Attempts to validate a federation between an ArcGIS Enterprise portal and ArcGIS Server site fail, and the following error is returned:

Error:
The server at <Portal_URL> returned an error. Could not decrypt token. Token may not be valid.

Cause

• Mismatch between the WebContextURL property and the ArcGIS Web Adaptor FQDN (port 443). When the ArcGIS Enterprise portal is upgraded, the WebContextURL property may be reset to blank.
• ArcGIS Enterprise portal is not federated with an ArcGIS Server site and the ArcGIS Server site is not assigned as the hosting server.

Solution or Workaround

Depending on the cause, the workarounds provided are applicable.

Update the WebContextURL property with the FQDN on the ArcGIS Web Adaptor port 443 binding

Update the WebContextURL property to match the FQDN on the web adaptor port 443 binding. Refer to the Portal for ArcGIS: Configure a portal to use a reverse proxy or load balancer for instructions.

Federate ArcGIS Enterprise portal with an ArcGIS Server site and assign it as the hosting server

Refer to Portal for ArcGIS: ArcGIS Server integration with ArcGIS Enterprise for instructions.

If the error persists even though the hosting server has been configured, ensure the server site is running.

1. On the ArcGIS Enterprise site, navigate to Organization > Settings > Servers.
2. Click Validate server sites.

If the server site fails to validate, ensure the ArcGIS Server service is running on Windows. On the server machine, navigate to Control Panel > System and Security > Windows Tools. In the Windows Tools window, double-click Services.

• If the Portal for ArcGIS service is not running, right-click the service and click Start.
• If the Portal for ArcGIS service is running, right-click the service and click Restart.