Python: werkzeug.exceptions.InternalServerError: 500 Internal Server Error: 'NoneType' object is not iterable

I've seen many solutions about this problem but any of them solved mine.

I've this INSERT query which is wrapped in a try/except and, although it works fine in the database (the data is properly inserted), a Traceback is called, the code jumps to the except and the code below the query execution is just ignored (which cannnot happen in my case).

It is something like this:

query = """
  INSERT INTO
    mytable(user_id, tcx_extension, user_email, created_date)
  VALUES
    {}
""".format("('12345678910', '6666', 'test123@test.com', '2020/01/06 00:00:00')")

self.pgsql.execute_query(query)  // the error is triggered here

//important code below that is ignored when the error fires

the self.pgsql.execute_query function is shown below:

def execute_query(self, query, retry=0, format=True):
    if self.pool is None:
        self._open_pool(PGSQL["connection_string"])

    try:
        conn = self.pool.getconn()

        cur = conn.cursor()
        conn.autocommit = True

        LOG.info("Executing query", extra={"query": query})
        cur.execute(query)

        if format is True:
            data = Formatter.format_cursor(cur)
        else:
            data = None
        self.pool.putconn(conn)
        cur.close()

   except pool.PoolError as e:
        LOG.error("PoolError: {}".format(e), extra={"query": query})
        if retry > MAX_RETRIES:
            raise TooManyRetries("Too many retries: {}".format(e))

        LOG.info("Will retry: {}".format(e), extra={"query": query})
        time.sleep(1)
        return self.execute_query(query, retry + 1)

    return data

The Traceback is shown below:

[2021-01-06 15:28:15,421] ERROR in app: Exception on /members/manage_socket_members [POST]
Traceback (most recent call last):
  File "C:\Users\artur.santos\AppData\Local\Programs\Python\Python37\lib\site-packages\flask\app.py", line 1612, in full_dispatch_request
    rv = self.dispatch_request()
  File "C:\Users\artur.santos\AppData\Local\Programs\Python\Python37\lib\site-packages\flask\app.py", line 1598, in dispatch_request
    return self.view_functions[rule.endpoint](**req.view_args)
  File "C:\Users\artur.santos\AppData\Local\Programs\Python\Python37\lib\site-packages\flask_restful\__init__.py", line 480, in wrapper
    resp = resource(*args, **kwargs)
  File "C:\Users\artur.santos\AppData\Local\Programs\Python\Python37\lib\site-packages\flask\views.py", line 84, in view
    return self.dispatch_request(*args, **kwargs)
  File "C:\Users\artur.santos\AppData\Local\Programs\Python\Python37\lib\site-packages\flask_restful\__init__.py", line 595, in dispatch_request
    resp = meth(*args, **kwargs)
  File "C:\Users\artur.santos\Documents\#salesforce\rc-analytics-api\src\decorators\auth.py", line 70, in wrap
    return f(*args, **kwargs)
  File "C:\Users\artur.santos\Documents\#salesforce\rc-analytics-api\src\members\manage_socket_members.py", line 30, in post
    return abort(500, error)
  File "C:\Users\artur.santos\AppData\Local\Programs\Python\Python37\lib\site-packages\werkzeug\exceptions.py", line 707, in abort
    return _aborter(status, *args, **kwargs)
  File "C:\Users\artur.santos\AppData\Local\Programs\Python\Python37\lib\site-packages\werkzeug\exceptions.py", line 687, in __call__
    raise self.mapping[code](*args, **kwargs)
werkzeug.exceptions.InternalServerError: 500 Internal Server Error: 'NoneType' object is not iterable

Any ideas on how to solve this?

EDIT 1: All the table fields are of type 'VARCHAR' except for the created_date.

EDIT 2: When I try to insert some values between double quotes the error changes (which is also a nonsense error for me). I don't know if gets me closer to the solution. Check it out the logs I printed

> query: INSERT INTO wfm.socket_user_relation (user_id, tcx_extension, user_email, created_date) VALUES (12345678937, 63, "test37@test.com.br", "2021/01/07 09:25:35")
> exception: column "test37@test.com.br" does not exist
LINE 1: ...ser_email, created_date) VALUES (12345678937, 63, "test37@te...
                                                             ^

EDIT 3: If I try to INSERT all of them double quoted, the error remains the same: Error: 500 Internal Server Error: 'NoneType' object is not iterable