Just got this error from our production job - PrefectHTTPStatusError: Server error '503 Service Unavailable' Does that mean Prefect Cloud was down for a moment?

I don't believe so. Was it a one off error? You can configure retries on your client to retry for HTTP related errors https://docs.prefect.io/2.13.7/api-ref/prefect/settings/?h=codes#prefect.settings.PREFECT_CLIENT_MAX_RETRIES

Thanks James.! Today is the first time we had two Prefect Flow jobs failed due to this reason at the same time after on Prefect for a couple of months.

We also had an issue 40 minutes ago

Interesting, I'll see what I can find out. Hopefully, it doesn't happen any more, but I'll see if any other users report this