Firebolt queries fail after idle: engine auto-stopped, check AUTO_START

TL;DR

If Firebolt queries fail intermittently on a schedule, check the engine state first: run SHOW ENGINES or query informationschema.engineshistory to see whether auto-stop parked it.

Steps

1. If Firebolt queries fail intermittently on a schedule, check the engine state first: run SHOW ENGINES or query informationschema.engineshistory to see whether auto-stop parked it. Fix it by setting AUTO_START=TRUE on the engine so an incoming query wakes it, or route control-plane and catalog queries through the system engine, which is always available. When scripting against Firebolt, always allow for cold-start latency on the first query after an idle period.

When to use

You are seeing this: When scripting against Firebolt, always allow for cold-start latency on the first query after an idle period. Use this skill when you run into "Firebolt queries fail after idle: engine auto-stopped, check AUTO_START".

When not to use

If your error message or symptom does not match what is described above, this is probably not your fix. Search for your exact error text instead of forcing this one to fit.

Versions

No specific versions are mentioned in the source material, so treat the fix as generally applicable and check the examples against whatever you have installed.

Why this happens

The original report does not dig into a root cause. It documents the symptom and the fix that resolved it.

Source: Official Firebolt docs (ALTER ENGINE / CREATE ENGINE): engines auto-stop after 20 minutes of idle time by default, and a stopped engine does not answer queries sent directly to its engine URL unless AUTOSTART is TRUE. Agents running scheduled scripts or API calls against a named engine will intermittently fail with the engine stopped after idle periods, even though the same query worked an hour ago. AUTOSTART defaults to true on CREATE ENGINE, but ALTER ENGINE or admin changes can set it false; the failure then looks like a connectivity or credentials problem rather than a stopped engine.

Verified resolution: If Firebolt queries fail intermittently on a schedule, check the engine state first: run SHOW ENGINES or query informationschema.engineshistory to see whether auto-stop parked it. Fix it by setting AUTO_START=TRUE on the engine so an incoming query wakes it, or route control-plane and catalog queries through the system engine, which is always available. When scripting against Firebolt, always allow for cold-start latency on the first query after an idle period.

Source URL: https://docs.firebolt.io/reference-sql/commands/engines/alter-engine