I am attempting to bulk write some JSON data to a ThingSpeak channel using the API. An example payload is: % Payload is data = { 'write_api_key': <my_api_write_key>, 'updates': [ {'field5': 833.205, 'field4': 6, 'field3': 775.648, 'field2': 24.2523, 'delta_t': 1, 'field1': 59.1391}, {'field5': 833.199, 'field4': 6, 'field3': 771.03, 'field2': 24.2844, 'delta_t': 2, 'field1': 59.1331}, {'field5': 833.208, 'field4': 6, 'field3': 750.343, 'field2': 24.3008, 'delta_t': 3, 'field1': 59.1405}, {'field5': 833.208, 'field4': 7, 'field3': None, 'field2': 24.2903, 'delta_t': 5, 'field1': 59.1479}, {'field5': 833.216, 'field4': 7, 'field3': 748.45, 'field2': 24.2965, 'delta_t': 6, 'field1': 59.1686}, {'field5': 833.21, 'field4': 8, 'field3': None, 'field2': 24.2914, 'delta_t': 7, 'field1': 59.1756}, {'field5': 833.204, 'field4': 8, 'field3': 738.847, 'field2': 24.2867, 'delta_t': 8, 'field1': 59.1943}, {'field5': 833.208, 'field4': 8, 'field3': 732.472, 'field2': 24.2814, 'delta_t': 10, 'field1': 59.1964}, {'field5': 833.212, 'field4': 8, 'field3': None, 'field2': 24.2599, 'delta_t': 11, 'field1': 59.1971}, {'field5': 833.207, 'field4': 8, 'field3': 737.475, 'field2': 24.2658, 'delta_t': 12, 'field1': 59.2122}, {'field5': 833.212, 'field4': 8, 'field3': None, 'field2': 24.2498, 'delta_t': 14, 'field1': 59.2161}, {'field5': 833.209, 'field4': 7, 'field3': 749.432, 'field2': 24.2503, 'delta_t': 15, 'field1': 59.2298}, {'field5': 833.208, 'field4': 7, 'field3': 760.224, 'field2': 24.2396, 'delta_t': 16, 'field1': 59.2308} ] } I am sending this payload programatically, in Python, with the requests library using the following command: response = requests.post(url='https://api.thingspeak.com/channels/<my_channel_id>/bulk_update.json', ... data=json.dumps(data)) This results in the response below: % Response { "status": "401", "error": { "error_code":"error_auth_required", "message":"Authorization Required", "details":"Please provide proper authentication details." } } I am certain that the API write key and channel_id are correct. I have used both for single writes successfully. I am using a free ThingSpeak account. I have also tried adding headers to the requests.post() call to indicate explicitly that this is json data. I'm not sure why this is occuring and would sincerely appreciate any pointers.