Unable to add Nearmap imagery services to Portal for ArcGIS

Description

Attempts to add Nearmap imagery services containing multiple date ranges of web maps as Open Geospatial Consortium (OGC) Web Map Services (WMS) to Portal for ArcGIS fail, and return the following error message:

Error:   
Service " does not exist or is inaccessible.

Cause

Portal for ArcGIS cannot read or trust Nearmap's server certificates. This is because no Nearmap’s root or intermediate certificates are imported into the Portal for ArcGIS keystore.

Solution or Workaround

Import Nearmap’s root or intermediate certificates into the Portal for ArcGIS keystore

1. Navigate to the web browser and paste the URL of the Nearmap WMS layer. Press Enter. In this example, Google Chrome is used.
2. Click the View site information icon next to the URL. Click Connection is secure > Certificate is valid.

3. In the Certificate Viewer window, click the Details tab. Select the root certificate and click Export….

4. In the Save As window, edit the name of the file, if required, and select DER-encoded binary, single certificate (*.der) for Save as type. Click Save.

5. Import the exported certificates into the Portal for ArcGIS keystore. Refer to Portal for ArcGIS: Import the root CA certificate for instructions.

Note:
If the error persists, check the proxy capability of Portal for ArcGIS and ensure the root or intermediate certificates are imported properly. 

Alternatively, import the certificates into the operating system's certificate store. Refer to ArcGIS Server: Import the certificate into the OS certificate store for more information.