SecureAuth version affected: All
After migrating realms to a new IdP or performing an upgrade, the following error is seen when accessing a SAML realm that uses a signing cert:
Error: at MFC.WebApp.SecureAuth.SAML20IdPInit.CreateSAMLResponse(String sUser, String UserID) at MFC.WebApp.SecureAuth.SAML20IdPInit.Page_Load(Object sender, EventArgs e)
The signing certificate lacks correct permissions or is not in a usable state.
Export the certificate then re-import it into cert store for the newly upgraded IdP server making sure it has correct permissions.