prestodb/presto · critical · PrestoException

REST_SERVER_FUNCTION_FETCH_ERROR

REST_SERVER_FUNCTION_FETCH_ERROR

Error message

Failed to fetch function definitions from REST server:

What it means

RestBasedFunctionApis.getFunctionsAt wraps all failures of the HTTP call to the remote function server (connection errors, timeouts, non-2xx responses, malformed JSON) into a PrestoException with code REST_SERVER_FUNCTION_FETCH_ERROR. It signals that function definitions could not be retrieved from the REST endpoint, with the underlying cause's message appended.

Source

Thrown at presto-function-namespace-managers/src/main/java/com/facebook/presto/functionNamespace/rest/RestBasedFunctionApis.java:107

    }

    private UdfFunctionSignatureMap getFunctionsAt(String endpoint)
            throws IllegalStateException
    {
        try {
            URI uri = uriBuilderFrom(URI.create(restUrl))
                    .appendPath(endpoint)
                    .build();
            Request request = Request.builder()
                    .prepareGet()
                    .setUri(uri)
                    .build();

            Map<String, List<JsonBasedUdfFunctionMetadata>> nativeFunctionSignatureMap = httpClient.execute(request, createJsonResponseHandler(functionSignatureMapJsonCodec));
            return new UdfFunctionSignatureMap(ImmutableMap.copyOf(nativeFunctionSignatureMap));
        }
        catch (Exception e) {
            throw new PrestoException(REST_SERVER_FUNCTION_FETCH_ERROR, "Failed to fetch function definitions from REST server: " + e.getMessage(), e);
        }
    }
}

View on GitHub (pinned to 55bb57d202)

Solutions

Check the embedded cause message and verify the REST server is up: curl the configured functions endpoint from the coordinator host
Fix catalog properties (rest server URL, endpoint path, auth) to point at the correct, reachable server
Check network path (DNS, firewall, proxy) and retry once the server is healthy; ensure server response format matches the expected JSON codec

Example fix

// before
function-namespace.url=http://functions-internal:8080/wrong-path
// after
function-namespace.url=http://functions-internal:8080/v1/functions

Defensive patterns

Strategy: retry

Validate before calling

// Pre-flight: ensure the REST server answers before planning queries
HttpResponse<String> resp = sendGet(restServerUrl + "/v1/functions/health");
if (resp.statusCode() != 200) throw new IllegalStateException("REST function server unhealthy");

Try / catch

try {
    functions = manager.getFunctions(functionName);
} catch (PrestoException e) {
    if (e.getErrorCode().getName().equals("REST_SERVER_FUNCTION_FETCH_ERROR")) {
        // retry with backoff; log cause from e.getCause()
    } else throw e;
}

Prevention

Monitor the REST function server's health from coordinator hosts
Validate catalog REST URL/credentials after every config change
Set client timeouts and retries for the function-namespace HTTP client
Keep server response schema in sync with the client JSON codec on upgrades

When it happens

Trigger: Calling getAllFunctions or getFunctions when the REST server is unreachable, returns an HTTP error, times out, or returns a body that fails JSON decoding into UdfFunctionSignatureMap.

Common situations: REST function service down or redeploying; wrong REST server URI in catalog config; network/firewall or DNS issues from coordinator; server returning an unexpected payload after an API version change; missing auth credentials causing 401/403.

Related errors

AI-assisted analysis of prestodb/presto@55bb57d202 (2026-09-04). Data as JSON: /api/errors/70242d25ff87beaa. Report an issue: GitHub.