PYTHON DROPBOX API process been hang since CLOSE_WAIT socket is not closed

Question

So I have my application running on windows for 5 years now. I have around 800 processes running in 5 different Machines. 5 / day lately are hanging on this:

I also managed to find the socket pid and kill it, than the app closed properly.

My code is the same regarding dropbox ...was not changed.

mt code flow:

self.uploading_thread = None
...
if self.uploading_thread:
    self.uploading_thread.join()  # wait if last one did not finish
self.uploading_thread = threading.Thread(target=self.update_server_data)
self.uploading_thread.start()

    def update_server_data(self):
        status = 'xsaxasxsa'
        self.statistics_server_o.set_data(status)

    def set_data(self, data):
        self.lock.acquire()
        self.data = data
        self.lock.release()

        # notify thread on new data
        self.new_data_flag.set()

    def update_server(self):
        while self.new_data_flag.wait():

            # clear flag
            self.new_data_flag.clear()

            if self.stop_event:
                break

            local_data_copy = self.get_hard_copy_data()

            # update new data
            try:
                self.dropbox_o.upload_bytes(local_data_copy, '', 'status', '{}_status.txt'.format(self.account_name),
                                            overwrite=True)
            except:
                pass

I can call the update thread many times, it async, so I wait until last job finish before I trigger a new one.

can you see anything related to my code ? should I add termination of the tread with timer ?