At 22:52 UTC on 21 October (15:52 PDT), GitHub experienced a network partition and subsequent database failure. This has caused intermittent issues with webhook delivery and other events that CircleCI depends on to manage your CircleCI workflows and jobs. The downtime has also prevented us from making API calls to GitHub to check on authorization and project/organization status.
Until GitHub has ended their outage, we will be unable to know fully what changes or issues this has caused with your projects or jobs within our system. Furthermore, when GitHub does start delivering webhooks again, we will see a surge of jobs starting, and we will immediately scale in response and remain overprovisioned until the surge is complete.
If you have any questions or issues, please reply to this Discuss post, or file a ticket with our support team.
GitHub summary: https://blog.github.com/2018-10-21-october21-incident-report/