Fleetup constantly throwing errors

[GoldenCoins]

At the moment we keep getting the following error on allianceauth sent as a notification, multiple times per day:

Error accessing Fleetup API

Traceback (most recent call last):
File "/home/allianceserver/venv/auth/lib/python3.5/site-packages/allianceauth/fleetup/managers.py", line 57, in get_endpoint
r.raise_for_status()
File "/home/allianceserver/venv/auth/lib/python3.5/site-packages/requests/models.py", line 935, in raise_for_status
raise HTTPError(http_error_msg, response=self)
requests.exceptions.HTTPError: 404 Client Error: Not Found for url: http://api.fleet-up.com/Api.svc/myappkey/myfleetupuserid/myapicode/DoctrineFittings/%7B%7D

What is causing this and how should I fix it?

All our fittings are updating fine on allianceauth if changes are made on fleetup.
but going to that URL in a browser throws this back:

{"Success":false,"Message":"Not found - Doctrine {} not found.","CachedUntilUTC":"/Date(1527080961447)/","CachedUntilString":"2018-05-23 13:09:21","Code":50016,"Data":null}