What it requires. Record-triggered flows must not invoke external-system actions (External Services, HTTP callout actions, or other outbound integrations) on the immediate, synchronous path. External calls belong on an asynchronous path that runs after the record change commits.
Why it matters. A callout attempted while the record save transaction is open fails at runtime; asynchronous paths exist in record-triggered flows precisely to reach external systems after commit. The Well-Architected pattern is that flows involving external system callouts or long-running processes use asynchronous paths.
How to fix it. Move external-system actions onto a Run Asynchronously path or a scheduled path, with fault paths handling their failures on that path.
Is this rule worth checking?
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