OneLogin - Underscore in the preceding part of a domain URL can't be saved in the OpenID Connect (OIDC) connector (4383003)

OneLogin - Underscore in the preceding part of a domain URL can't be saved in the OpenID Connect (OIDC) connector

When using an OIDC app based on the OpenID Connect (OIDC) app connector, an Admin is not allowed to save Redirect URIs with URLs containing an underscore character in the domain URL. 

The app errors with a message saying "Redirect URIs are invalid, please check these URIs: https://local_host.redirect" 

Related to security patterns behind the connector built

The OL Admin needs to require the Relying Party (RP), the app provider, to change the URI for a different one with no underscore characters.

OpenID Connect (OIDC) Custom Connector > https://onelogin.service-now.com/support?id=kb_article&sys_id=2fd988e697b72150c90c3b0e6253af7f