Portal for ArcGIS sign in page allows only enterprise logins preventing administrators from signing in

Description

When an enterprise login is newly set up in Portal for ArcGIS, administrators may not have access to the Portal home page as the option for signing in with a built-in account is not available.

Cause

The Sign In Options of the enterprise login is set to 'Their Enterprise Login' only, as shown in the image below.

This option disables built-in user account logins and allows only enterprise logins.

Solution or Workaround

Reset the settings through ArcGIS Portal Directory.

1. Sign in to ArcGIS Portal Directory through the following URL:

https://<portal.domain.com>:7443/arcgis/sharing/rest/portals/self/update

2. Click on the Org ID : 0123456789ABCDEF
3. Scroll to the bottom, and click Update under Supported Operations.
4. Scroll to the Can SignIn Using ArcGIS radio button and select True.
5. Click Update Organization. The steps enable user account logins.

For ArcGIS 10.8.1 and above, re-enable the sign-in using ArcGIS through Postman. Refer to How To: Generate and use an ArcGIS Server token using Postman for more information. From the documentation, add the following key:value pair in step 5:

canSigninArcGIS: true

The following image shows a sample of the key:value pair set in Postman.