This breakage has now been rolled back from the Atlassian side. Rules are executing normally again.

Related Atlassian incident that caused this: https://status.atlassian.com/incidents/6cx2964jrpx5

Atlassian have verified that there was a bad Jira Cloud deploy this morning. They are now rolling back this deployment.

We'll continue to monitor error rates until this has been completed.

Since about 9:15 AM AEST, we're observing elevated error rates, authenticating webhooks requests from Jira Cloud. This seems to be caused by a breaking API change on Jira Cloud's side.

We'll continue to investigate.