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FSTL000 - Failed to Connect to the Fastly API

Agent error code #FSTL000 indicates the agent could not reach the Fastly API. The connection was never established, so nothing was written.

This is distinct from authentication failures (#FSTL001), authorization failures (#FSTL002), TLS errors (#FSTL003) and timeouts (#FSTL004). It covers a general connectivity failure, such as a refused connection or a DNS lookup that fails, and also an unmapped HTTP status from a server that did answer.

Common causes include:

  • The agent host has no outbound HTTPS (TCP 443) access to api.fastly.com
  • A proxy, firewall or VPN between the agent and Fastly is dropping the traffic
  • An API base URL override points somewhere that is not the Fastly API

Steps to Resolve

  1. From the agent host, confirm a request to https://api.fastly.com comes back with an HTTP status rather than a connection error
  2. If the agent goes out through a proxy, confirm the agent's proxy configuration includes it
  3. Clear the API base URL field unless you deliberately need an override
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