Certificates issues affecting API and proxy

Incident Report for Fly.io

Resolved

Between 19:54 and 20:06 UTC, our Vault cluster serving app certificates was unavailable. This caused various API requests to fail, mainly operations on certificates but also app creates and IP assignments.

As the failure mode was Vault requests hanging rather than failing immediately, TLS requests through fly-proxy for domains where the certificate was not cached on the local node remained open for a long time while proxy attempted to fetch the certificate; this caused some connections to fail as too many connection slots were taken up by requests waiting on Vault.

The root cause of this incident was a partially completed update to the Vault cluster. We will be implementing safeguards in the proxy for this failure mode, as well as improving certificate storage longer-term.

Posted Mar 03, 2026 - 00:54 UTC