IdP v5 external authentication error

[Paul B. Henson]

On Mon, Mar 17, 2025 at 01:27:42PM -0300, Martin Salvadori via users wrote:

> In Google Workspace (Google Admin console > Security > Authentication > SSO
> with third-party IdP), I configured the IdP name and uploaded the signing
> certificate generated during the IdP installation.
> The URL of the sign-in page points to the JSP page that implements external
> authentication: https://<MY_NGROK_HOST>/idp/external.jsp

You're pointing the SAML SP directly to your custom external auth page?
That's not right; the SP should send an auth request to the idp using
the appropriate binding as usual, the idp will then redirect to the
external auth page as part of handing the auth request.