apache/druid · error · IllegalStateException

Property[ ] not specified.

Error message

Property[%s] not specified.

What it means

PropUtils.getProperty fetches a property from a Properties object and treats absence as a fatal condition: if props.getProperty returns null (or the value is the empty string mapped as null), it throws IllegalStateException naming the missing key. It expresses 'this property is required'.

Solutions

1. Add the missing property to runtime.properties / the Properties object with a valid value
2. Verify the exact property name (typos and case) and that the config file is actually on the classpath/being loaded
3. Use props.getProperty(key, defaultValue) if the property is genuinely optional
4. Check version upgrade notes: the property may have been renamed or removed

Example fix

// before
String mode = PropUtils.getProperty(props, "druid.zk.service.compress.list"); // ISE if unset
// after
String mode = props.getProperty("druid.zk.service.compress.list", "list"); // or set the property in runtime.properties

String v = props.getProperty(key);
if (v == null) { throw new IllegalStateException("set required property " + key + " in runtime.properties"); }

try { String v = PropUtils.getProperty(props, key); } catch (IllegalStateException e) { /* supply default or fail fast with actionable message */ }

When it happens

Trigger: Calling getProperty(props, key) where the key was never set in the Properties object — missing runtime.properties entry, config not passed to an embedded node, or a typo'd property name.

Common situations: Deployments missing required druid.* config properties; renaming a property across Druid versions so old config files lack the new key; programmatic Properties built in tests missing keys; extensions reading properties not documented as required.

Understand the failure class

Background: "is required", "must be set", "missing required field": configuration validation errors across open-source libraries — this error's family across 36 libraries.

Related errors

• Can't load TrustStore. Truststore path or password is not…
• druid.request.logging.transportUrl must be set when…
• maxActiveProcessors[ ] < 1
• Property[ ] must be set
• unknown encoding strategy

AI-assisted analysis of apache/druid@9b90983fd2 (2026-09-07). Data as JSON: /api/errors/37b4dd09e215aeff. Report an issue: GitHub.

Appendix: source

Thrown at processing/src/main/java/org/apache/druid/common/utils/PropUtils.java:35

 * under the License.
 */

package org.apache.druid.common.utils;

import org.apache.druid.java.util.common.ISE;

import java.util.Properties;

/**
 */
public class PropUtils
{
  public static String getProperty(Properties props, String property)
  {
    String retVal = props.getProperty(property);

    if (retVal == null) {
      throw new ISE("Property[%s] not specified.", property);
    }

    return retVal;
  }

  public static int getPropertyAsInt(Properties props, String property)
  {
    return getPropertyAsInt(props, property, null);
  }

  public static int getPropertyAsInt(Properties props, String property, Integer defaultValue)
  {
    String retVal = props.getProperty(property);

    if (retVal == null) {
      if (defaultValue == null) {
        throw new ISE("Property[%s] not specified.", property);
      } else {

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