Same problem was seen in https://github.com/firebase/firebase-functions/issues/1510 for JS/TS ### Test case ```python from firebase_functions import https_fn from firebase_functions import logger @https_fn.on_request() def on_request_example(req: https_fn.Request) -> https_fn.Response: common_data = {"foo": "bar"} obj1 = { "data": common_data, } obj2 = { "data": common_data, } logger.debug("TEST 1", {"obj1": obj1, "obj2": obj2}) return https_fn.Response("Oki doki") ``` ### Steps to reproduce - Call the function - View the logs ### Expected behavior When calling the function (e.g. locally) it should log with the json payload: ```json { "obj1": { "data": { "foo": "bar" } }, "obj2": { "data": { "foo": "bar" } }, "severity": "DEBUG", "message": "TEST 1" } ``` ### Actual behavior Instead it prints the following payload: ```json { "obj1": { "data": { "foo": "bar" } }, "obj2": { "data": "[Circular]" }, "severity": "DEBUG", "message": "TEST 1" } ``` ### Were you able to successfully deploy your functions? Yes, I had the same issue when viewing the logs in the log explorer.