Failed to federate data store item

Error Message

When working in a distributed deployment of ArcGIS Enterprise 10.7.1, attempting to federate a data store item to Portal for ArcGIS from the ArcGIS Server admin endpoint returns the following error message:

Error:   
Failed to federate data store item <data_store_item_path>. Server machine 'https://machine.domain.com:7443/arcgis/sharing/rest/portals/0123456789ABCDEF/datastores/addToServer'; returned an error. 'Server is not reachable'.

The following error message is displayed in the Portal for ArcGIS logs:

Error:   
Invalid SSL certificate found. PKIX path building failed: sun.security.provider.certpath.SunCertPathBuilderException: unable to find valid certification path to requested target.

Cause

The entire chain of certificates is not imported in both the Portal for ArcGIS and ArcGIS Server admin endpoints. In a distributed environment, this impacts various functionality within the Portal for ArcGIS interface.

Solution or Workaround

Perform the following workaround to resolve:

1. Navigate to the Portal for ArcGIS admin endpoint, and log in with an administrator account.
2. Navigate to Security > SSLCertificates > Import Root or Intermediate Certificate.
3. Click Choose File, and select the chain of certificates to import. Click Import to begin the import process, and restart Portal for ArcGIS.
4. Navigate to the ArcGIS Server admin endpoint, and log in with an administrator account.
5. Navigate to machines > machine_name > sslcertificates > importRootOrIntermediate.
6. Click Choose File, and select the chain of certificates to import. Click Import to begin the import process, and restart ArcGIS Server.
7. Log in to the ArcGIS Server admin endpoint.
8. Navigate to data > federateDataItem. Enter the item path for the registered data store, and click Federate Data Item.

The operation completes successfully. To verify, log in to the Portal for ArcGIS home page, and select Content. The data store item is listed here.