stanfordnlp/CoreNLP · warning

Could not parse URL

Error message

Could not parse URL: ${uri}

What it means

WebServiceAnnotator.ping() validates that the configured server URI is reachable before annotating. When the URI string is malformed (cannot be converted to a URL), a MalformedURLException is caught and a warning is logged, and ping returns false so the annotator reports itself not ready.

Solutions

1. Fix the `uri` property to a fully qualified absolute URL, e.g. http://host:port.
2. Start the web service server and confirm the endpoint exists before running the pipeline.
3. Log/print the configured URI value to spot typos or unresolved property substitution.
4. If the URI comes from properties/environment, validate it with new URI(...) or URL parsing before constructing the annotator.

Example fix

// before
props.setProperty("webservice.uri", "localhost:9000");
// after
props.setProperty("webservice.uri", "http://localhost:9000");

try { new java.net.URL(uri); if (!uri.startsWith("http")) throw new IllegalArgumentException("uri must be http(s)"); } catch (java.net.MalformedURLException e) { throw new IllegalArgumentException("Bad service uri: " + uri); }

if (!annotator.ready()) { log.warn("Service unreachable or bad URI: " + uri); return fallbackAnnotate(input); }

When it happens

Trigger: Calling ready() or annotateImpl() when the `uri` option (e.g. serverUrl) is not a parseable absolute URL, such as a missing scheme ("localhost:9000"), illegal characters, or empty string.

Common situations: Setting webservice annotator properties with a typo in the URL, forgetting http:// prefix, using a relative path, or environment-specific config pointing at an unparseable endpoint.

Understand the failure class

Background: "Invalid URL" errors: why new URL(), URI.parse, and reqwest::Url reject your string — missing scheme, whitespace, and bad path format — this error's family across 39 libraries.

Related errors

• Not an HTTP URI
• Invalid subnet
• java.net.MalformedURLException
• Could not parse subnet
• Unknown LogPriorType:

AI-assisted analysis of stanfordnlp/CoreNLP@1b7edd19c4 (2026-09-10). Data as JSON: /api/errors/77604098245ebb0f. Report an issue: GitHub.

Appendix: source

Thrown at src/edu/stanford/nlp/pipeline/WebServiceAnnotator.java:200

  /**
   * A utility to ping an endpoint. Useful for {@link #live()} and {@link #ready(boolean initialTest)}.
   *
   * @param uri The URL we are trying to ping.
   *
   * @return True if we got any non-5XX response from the endpoint.
   */
  protected boolean ping(String uri) {
    try {
      URL url = new URL(uri);
      HttpURLConnection connection = (HttpURLConnection) url.openConnection();
      connection.setRequestProperty("Accept-Charset", "UTF-8");
      connection.setRequestMethod("GET");
      connection.connect();
      int code = connection.getResponseCode();
      return code < 500 || code >= 600;
    } catch (MalformedURLException e) {
      log.warn("Could not parse URL: " + uri);
      return false;
    } catch (ClassCastException e) {
      log.warn("Not an HTTP URI");
      return false;
    } catch (IOException e) {
      return false;
    }

  }


  /**
   * Start the actual server.
   *
   * @param command the command we are using to start the sever.
   *
   * @return True if the server was started; false otherwise.
   */

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