IdPv3 jetty9 back-channel setup help needed

[Cantor, Scott]

> So client receives a fairly generic error:

All errors are generic, that's a configuration setting. Unrelated, just noting it.

> jetty-base is the jetty-base dir in the idp unzipped source.

That isn't how you want to deploy Jetty. That directory is used for the Windows installer and is nothing but an example otherwise (if that). Do not use it directly. Certainly don't use it if it's not working.

> Naively, I suspect it's something connected to jetty9-dta-ssl-1.0.0.jar,
> but I can't have any logline about: net.shibboleth.utilities.jetty9, nor
> in shib logs, neither in jetty logs.

I seriously doubt it, but just don't use it, and if it turns into a different error involving authentication of the request, you'll have more proof.

> Whence should I start to pinpoint my error?

Use Jetty itself and configure it based on the documentation I provided in the wiki.
 
-- Scott