FrontendHaltNetworking·Advanced·Coding·1 min read
What is the purpose of a 409 Conflict status code?
Short interview answer
It signals that the request couldn't be completed because it conflicts with the current state of the resource, such as trying to create a record that already exists with a unique field, distinct from a plain validation failure.
Key takeaway
Explain the underlying mental model clearly, then support it with a concrete example and its trade-offs.