prestodb/presto · error · ProxyException

Bad status code from remote Presto server: %s: %s

Error message

Bad status code from remote Presto server: %s: %s

What it means

The proxy expects HTTP 200 (or 204) from the remote Presto server. Any other status is wrapped in a ProxyException with the status code and the response body embedded in the message. It means the backend rejected or failed the request at the HTTP level.

Source

Thrown at presto-proxy/src/main/java/com/facebook/presto/proxy/ProxyResponseHandler.java:53

        implements ResponseHandler<ProxyResponse, RuntimeException>
{
    private static final MediaType MEDIA_TYPE_JSON = MediaType.create("application", "json");

    @Override
    public ProxyResponse handleException(Request request, Exception exception)
    {
        throw new ProxyException("Request to remote Presto server failed", exception);
    }

    @Override
    public ProxyResponse handle(Request request, Response response)
    {
        if (response.getStatusCode() == NO_CONTENT.code()) {
            return new ProxyResponse(response.getHeaders(), new byte[0]);
        }

        if (response.getStatusCode() != OK.code()) {
            throw new ProxyException(format("Bad status code from remote Presto server: %s: %s", response.getStatusCode(), readBody(response)));
        }

        String contentType = response.getHeader(CONTENT_TYPE);
        if (contentType == null) {
            throw new ProxyException("No Content-Type set in response from remote Presto server");
        }
        if (!MediaType.parse(contentType).is(MEDIA_TYPE_JSON)) {
            throw new ProxyException("Bad Content-Type from remote Presto server:" + contentType);
        }

        try {
            return new ProxyResponse(response.getHeaders(), toByteArray(response.getInputStream()));
        }
        catch (IOException e) {
            throw new ProxyException("Failed reading response from remote Presto server", e);
        }
    }

View on GitHub (pinned to 55bb57d202)

Solutions

  1. Read the status code and body in the message to identify the backend's complaint.
  2. Fix authentication if 401/403 (check forwarded credentials/bearer token setup).
  3. Correct the remote server URI/port if 404.
  4. If 500/503, check backend Presto coordinator logs and health.
Defensive patterns

Strategy: try-catch

Validate before calling

// check the endpoint returns 200 before issuing real work
const probe = await fetch(backendUri + path, { method: "HEAD", headers });
if (![200, 204].includes(probe.status)) throw new Error("Backend status " + probe.status);

Try / catch

try {
  return await proxyCall(req);
} catch (e) {
  const m = /Bad status code .*?: (\d+):/.exec(String(e.message));
  if (m) {
    const status = Number(m[1]);
    if (status === 401 || status === 403) refreshCredentials();
    else if (status === 503) scheduleRetry();
  }
  throw e;
}

Prevention

When it happens

Trigger: Remote server returned e.g. 401/403 (auth), 404 (wrong URI/path), 500 (internal error), or 503 (unavailable) for a proxied call; the body is included via readBody(response).

Common situations: Expired/missing bearer token forwarded to backend; wrong remote server port or context path; backend returning 503 during restart or overload.

Related errors

AI-assisted analysis of prestodb/presto@55bb57d202 (2026-09-04). Data as JSON: /api/errors/c37633aa73c3276d. Report an issue: GitHub.