Add Item By URL - WFS with Custom Parameters

[GISP00]

Using ArcGIS Portal 11.5 I am trying to add a layer to a web map using a URL that is a WFS service type. If I paste the full URL in a new web browser tab it it works. But when I try use the Add Item By URL option and the custom parameters, the error is service does not exist or is inaccessible.  

Screenshots attached to help convey the problem and settings.

[TimoT]

Is the WFS publicly accessible or secured?

Given that the WFS XML loads directly in the browser, the next most common causes of this error in my experience are:

1. Cross-Origin Resource Sharing (CORS) issues

Open your browser’s developer tools (hotkey F12), reproduce the error, and check the console tab for CORS-related messages. Sample reference image below:

If you see this type of error, you'll likely need the WFS host to whitelist your domain.

2. TLS handshake/validation errors

These types of errors can vary, and diagnosing them is challenging without full URL details that have been sanitized in your images. To check for issues of this nature:

1. Use developer tools to inspect the request URL. Is it directed to the WFS URL, or is it routed through the Portal's proxy (e.g., https://portal.domain.com/portal/sharing/proxy?https://[wfs-url])?
2. Have you configured your Portal to restrict the proxy capability?
3. Log into the Portal Directory (/portal/sharing/rest) and navigate to Home > Portals > checkUrl. Enter your WFS URL, and if it returns anything other than a 200 status response, it could indicate that your Portal can’t verify the TLS certificate.