AWS Lambda Chalice: "The request could not be satisfied" Error

Question

I want my lambda function to return the response of another lambda function invoked via AWS API Gateway.

Both functions are deployed by Lambda Chalice to different APIs.

When the first function sends a request to the 2nd functions API endpoint, I am getting an error response saying that "The request could not be satisfied".

Any help is appreciated.

Edit to include some code as requested; shortened for brevity:

@app.route('/verify_user_token', methods=['GET'], cors=True)
def verify_user_token():
    request = app.current_request
    params = request.query_params or {}

    # do your things here; if all goes well:

    r = requests.get(ANOTHER_AWS_API_GATEWAY_ENDPOINT_URL, data=params)

    return r.text