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Troubleshooting issues with HTTP API JWT authorizers

The following provides troubleshooting advice for errors and issues that you might encounter when using JSON Web Token (JWT) authorizers with HTTP APIs.

Issue: My API returns 401 {"message":"Unauthorized"}

Check the www-authenticate header in the response from the API.

The following command uses curl to send a request to an API with a JWT authorizer that uses $request.header.Authorization as its identity source.

$curl -v -H "Authorization: token" https://api-id.execute-api.us-west-2.amazonaws.com/route

The response from the API includes a www-authenticate header.

...
< HTTP/1.1 401 Unauthorized
< Date: Wed, 13 May 2020 04:07:30 GMT
< Content-Length: 26
< Connection: keep-alive
< www-authenticate: Bearer scope="" error="invalid_token" error_description="the token does not have a valid audience"
< apigw-requestid: Mc7UVioPPHcEKPA=
<
* Connection #0 to host api-id.execute-api.us-west-2.amazonaws.com left intact
{"message":"Unauthorized"}}

In this case, the www-authenticate header shows that the token wasn't issued for a valid audience. For API Gateway to authorize a request, the JWT's aud or client_id claim must match one of the audience entries that's configured for the authorizer. API Gateway validates client_id only if aud is not present. When both aud and client_id are present, API Gateway evaluates aud.

You can also decode a JWT and verify that it matches the issuer, audience, and scopes that your API requires. The website jwt.io can debug JWTs in the browser. The OpenID Foundation maintains a list of libraries for working with JWTs.

To learn more about JWT authorizers, see Control access to HTTP APIs with JWT authorizers in API Gateway.