SteadyNode

Vercel · HTTP 502

Vercel 502: NO_RESPONSE_FROM_FUNCTION

Diagnose Vercel NO_RESPONSE_FROM_FUNCTION when an invocation exits without a valid HTTP response. Check handler return paths, crashes, and runtime logs.

Origin / Application

Decode a CDN or gateway error

Paste a captured HTTP response or enter a status and headers. Only the status and response headers are sent; common credential headers are filtered first.

Supports raw headers, full HTTP responses, JSON with status/statusCode and headers, cURL -v/-i response output, and HAR exports. HAR selects a server error first. cURL commands are never executed; request headers, response bodies, and common credential headers are excluded.

Diagnostic report

Error code / name

VERCEL-NO_RESPONSE_FROM_FUNCTION

Fault domain

Origin / Application

Why it happened

The function started but did not produce a valid response before exiting. An unhandled exception, missing return branch, process termination, or malformed adapter response can leave the edge with no payload.

Actionable fixes

  1. Inspect runtime logs for the x-vercel-id and identify the first uncaught exception or process exit.
  2. Return a Response on every handler path and validate the function adapter's expected response shape.
  3. Add a bounded error handler that logs a correlation ID and returns a controlled 5xx response.

Why this error happened

The function started but did not produce a valid response before exiting. An unhandled exception, missing return branch, process termination, or malformed adapter response can leave the edge with no payload.

Actionable fixes

  1. Inspect runtime logs for the x-vercel-id and identify the first uncaught exception or process exit.
  2. Return a Response on every handler path and validate the function adapter's expected response shape.
  3. Add a bounded error handler that logs a correlation ID and returns a controlled 5xx response.

Network failure point

Client -> Vercel Edge -> function invocation -> throw/exit without Response -> X

Verify origin directly via CLI

curl -sS -v --max-time 30 https://example.com/api/health -o /dev/null

Configuration fix

app/api/health/route.tstypescript
export async function GET() {
  try {
    return Response.json({ status: "ok" });
  } catch {
    return Response.json({ error: "Internal server error" }, { status: 500 });
  }
}

Catch this failure before it becomes an outage

SteadyNode's HTTP checks retain provider response headers and status codes, while Upstream Translator helps separate function crashes from edge routing failures.

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Frequently asked questions

What causes NO_RESPONSE_FROM_FUNCTION?

The invocation ended without a valid response, often due to an unhandled exception, a missing return, or a runtime exit.

Can a successful local function still return this error?

Yes. Deployment environment variables, runtime versions, and production-only dependency failures can change the deployed execution path.

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