How to fix Azure FHIR service import failure

I am using $import operation to import data into Azure FHIR service. I am using ndjson format. Part of my code is below:

def import_data2FHIR(access_token, file_info):
    # Azure FHIR service URL
    fhir_service_url = "https://<my_fhir_service>.fhir.azurehealthcareapis.com"

    # Set up the headers with the token
    headers = {
        "Authorization": f"Bearer {access_token}",
        'Prefer': 'respond-async',
        'Content-Type': 'application/fhir+json'
    }

    # Example FHIR resource (Patient)
    fhir_resource = {
        "resourceType": "Parameters",
        "parameter": [
            {
                "name": "inputFormat",
                "valueString": "application/fhir+ndjson"
            },
            {
                "name": "mode",
                "valueString": "InitialLoad",
            },
            {
                "name": "input",
                "part": [
                    {
                        "name": "url",
                        "valueUri": file_info["url"]
                    },
                    {
                        "name": "etag",
                        "valueUri": file_info["etag"]
                    }
                ]
            }
        ]
    }

    # POST the FHIR resource to the FHIR server
    response = requests.post(f"{fhir_service_url}/$import", json=fhir_resource, headers=headers)

    # Check the response
    if response.status_code == 201:
        print("Resource created successfully")
        print("Response:", response.json())
    else:
        print("Failed to create resource")
        print("Status Code:", response.status_code)
        print("Response:", response.json())

if __name__ == "__main__":
    access_token = get_token() # I get my access token successfully
    file_info = {"url": "https://<my_storage_account>.blob.core.windows.net/tmp-file-system/my-directory/patient-fhir-data-2019Jul10-0903.ndjson",
                 "etag": "0x8DC9402319782B2"}
    import_data2FHIR(access_token, file_info8)

<my_fhir_service> has been already assigned to Contributor and Storage Blob Data Contributor role to <my_storage_account>. But I got status code 202 with error:

Traceback (most recent call last):
  File "D:\code_for_python\FHIR_service_import.py", line 112, in <module>
    import_data2FHIR(access_token, file_info8)
  File "D:\code_for_python\FHIR_service_import.py", line 85, in import_data2FHIR
    print("Response:", response.json())
  File "D:\anaconda3\envs\Epic\lib\site-packages\requests\models.py", line 978, in json
    raise RequestsJSONDecodeError(e.msg, e.doc, e.pos)
requests.exceptions.JSONDecodeError: Expecting value: line 1 column 1 (char 0)

Would you please help how to troubleshoot this issue? I really appreciate your help.