Unable to decode incoming request

[Michael Dahlberg]

I'm working with an SP that has provided their metadata to me.  I've made
the necessary configuration changes to our IdP.  However, when I navigate
to their test URL, I'm returned back to our IdP with a "Something went
wrong" error page. The log entries state that its unable to decode the
incoming request (they're using RSA +SHA1 for signing) which is immediately
followed by a opensaml error:

Shibboleth Authentication Request message did not contain the providerId
query parameter.

I don't think the problem is the lack of a providerID, just that we can't
decode the incoming request which probably contains the providerId.  I've
checked the X509 cert in their metadata and it looks good.  Are there any
other reasons why the IdP would be unable to decode the request?

Thanks,
Mike
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