apache/druid · error · IllegalArgumentException

URI[ ] has no host

Error message

URI[%s] has no host

What it means

ServiceLocation.fromUri() maps a java.net.URI to a ServiceLocation, which requires a host. A null URI or a URI with no host component (e.g., a relative URI like "/status" or scheme-only "localhost:8080" misparsed) throws an IllegalArgumentException.

Solutions

1. Ensure the URI string includes scheme and host, e.g., "http://broker:8082".
2. Fix strings like "host:port" by prefixing a scheme: new URI("http://" + hostPort).
3. Null-check the URI before calling fromUri().
4. Validate addresses at config load with a URI parser that requires host.

Example fix

// before
ServiceLocation loc = ServiceLocation.fromUri(new URI("broker.internal:8082")); // no host
// after
ServiceLocation loc = ServiceLocation.fromUri(new URI("http://broker.internal:8082"));

if (uri == null || uri.getHost() == null) { throw new IllegalArgumentException("URI must include a host: " + uri); }

boolean hasHost(URI u) { return u != null && u.getHost() != null; }

try { return ServiceLocation.fromUri(uri); } catch (IllegalArgumentException e) { if (e.getMessage().endsWith("has no host")) { throw new IllegalArgumentException("Provide scheme-qualified URI like http://host:port, got: " + uri); } throw e; }

When it happens

Trigger: Calling ServiceLocation.fromUri() with null, with a relative URI lacking authority, or with a string like "host:port" that URI parses as scheme "host" and no host.

Common situations: Parsing service addresses from config strings without a scheme (e.g., "broker:8082" becomes scheme=broker, no host); placeholder/empty URIs in cluster metadata; unvalidated inputs from external services.

Understand the failure class

Background: "Invalid URL" / "URL cannot be empty": fix the malformed or missing URL behind request-construction failures — this error's family across 50 libraries.

Related errors

• Invalid maxAttempts[ ] in retry policy
• One or more values are required for parameter
• Path must start with '/'
• A local input source accepts only one of
• A local input source can set parameter

AI-assisted analysis of apache/druid@9b90983fd2 (2026-09-07). Data as JSON: /api/errors/45f05fc9f10bd433. Report an issue: GitHub.

Appendix: source

Thrown at server/src/main/java/org/apache/druid/rpc/ServiceLocation.java:87

  }

  /**
   * Create a service location based on a {@link DruidNode}, without a base path.
   */
  public static ServiceLocation fromDruidNode(final DruidNode druidNode)
  {
    return new ServiceLocation(druidNode.getHost(), druidNode.getPlaintextPort(), druidNode.getTlsPort(), "");
  }

  /**
   * Create a service location based on a {@link URI}.
   *
   * @throws IllegalArgumentException if the URI cannot be mapped to a service location.
   */
  public static ServiceLocation fromUri(final URI uri)
  {
    if (uri == null || uri.getHost() == null) {
      throw new IAE("URI[%s] has no host", uri);
    }

    final String scheme = uri.getScheme();
    final String host = stripBrackets(uri.getHost());
    final StringBuilder basePath = new StringBuilder();

    if (uri.getRawPath() != null) {
      if (uri.getRawQuery() == null && uri.getRawFragment() == null && uri.getRawPath().endsWith("/")) {
        // Strip trailing slash if the URI has no query or fragment. By convention, this trailing slash is not
        // part of the service location.
        basePath.append(uri.getRawPath(), 0, uri.getRawPath().length() - 1);
      } else {
        basePath.append(uri.getRawPath());
      }
    }

    if (uri.getRawQuery() != null) {
      basePath.append('?').append(uri.getRawQuery());

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