Error 500 when trying to authenticate with app

[Francesca Ricci-Tam]

Hello,

I have registered a confidential patient-facing app (still in development, not production) and got a client ID and client secret for it, and I have been trying to connect with it to the CMS Blue Button API. When the app launches, the authorizeUri and tokenUri obtained by our fhir client (which uses the SMART library) from the BlueButton metadata are correct, but it does not redirect me to the Medicare authorization page; instead, I just end up with server error 500:

{"error": "Server Error (500)"}

Here is the URL where it occurs, with the client id redacted:

https://sandbox.bluebutton.cms.gov/v2/o/authorize/?response_type=code&client_id=${MY_CLIENT_ID}&scope=profile%20patient%2FPatient.read%20patient%2FCoverage.read%20patient%2FExplanationOfBenefit.read&redirect_uri=https%3A%2F%2F127.0.0.1%3A3000%2Fapi%2Fv1%2Fehr%2Fbluebutton%2Fapp&aud=https%3A%2F%2Fsandbox.bluebutton.cms.gov%2Fv2%2Ffhir&state=NB8yRvjso2ajDbF4

I have no problem using the test client to authenticate on Medicare with one of the test patients and get an access token, and I also checked that I am logged out of the developer portal, but I still get this error 500 when I try to initiate the oauth workflow with my app using its client id and secret.
Is there something going on with the Blue Button server at present, or is there something I might still be doing incorrectly?
Thank you,

Francesca Ricci-Tam