Unable to configure ArcGIS Web Adaptor (IIS) with ArcGIS Server and Portal for ArcGIS

Description

Attempts to configure either Portal for ArcGIS, ArcGIS Server, or both with ArcGIS Web Adaptor (IIS) in an ArcGIS Enterprise deployment fail, and one of the following error messages is returned on the Web Adaptor configuration page.

Portal for ArcGIS

Error:   
Unable to configure Portal for ArcGIS with the web adaptor. Please make sure that the Portal for ArcGIS machine is running and that the account specified has administrative privileges to the Portal.

ArcGIS Server

Error:   
Unable to configure the ArcGIS Server site with the web adaptor. Please make sure that the machine hosting the site is running and that the account specified has administrative privileges.

Cause

The incorrect administrator or primary site administrator credentials are used on the ArcGIS Web Adaptor (IIS) configuration page. Refer to ArcGIS Enterprise: Configure ArcGIS Web Adaptor with Portal for ArcGIS and ArcGIS Enterprise: Configure ArcGIS Web Adaptor with a server site for information regarding the credentials used during the ArcGIS Web Adaptor (IIS) configuration.

Solution or Workaround

On the ArcGIS Web Adaptor (IIS) configuration page, use the correct administrator or primary site administrator credentials to configure either Portal for ArcGIS, ArcGIS Server, or both with ArcGIS Web Adaptor (IIS). If a temporary administrator account is required to configure Portal for ArcGIS with ArcGIS Web Adaptor (IIS), refer to Portal for ArcGIS: Recovering the portal when no administrator accounts are available for instructions. If a credential reset is required for the primary site administrator account, refer to ArcGIS Server: Reset the primary site administrator's password for instructions.