languagetool-org/languagetool · error · IllegalArgumentException

maxWorkQueueSize must be >= 0:

Error message

maxWorkQueueSize must be >= 0: 

What it means

The maxWorkQueueSize property from the server configuration file is parsed and validated; negative values are rejected with this IllegalArgumentException. maxWorkQueueSize bounds the request work queue; 0 means unbounded, so it must be >= 0.

Source

Thrown at languagetool-server/src/main/java/org/languagetool/server/HTTPServerConfig.java:343

        maxCheckTimeMillisAnonymous = maxCheckTimeMillisLoggedIn = maxCheckTimeMillisPremium = Integer.parseInt(getOptionalProperty(props, "maxCheckTimeMillis", "-1"));
        maxCheckTimeMillisAnonymous = Long.parseLong(getOptionalProperty(props, "maxCheckTimeMillisAnonymous", String.valueOf(maxCheckTimeMillisAnonymous)));
        maxCheckTimeMillisLoggedIn = Long.parseLong(getOptionalProperty(props, "maxCheckTimeMillisLoggedIn", String.valueOf(maxCheckTimeMillisLoggedIn)));
        maxCheckTimeMillisPremium = Long.parseLong(getOptionalProperty(props, "maxCheckTimeMillisPremium", String.valueOf(maxCheckTimeMillisPremium)));
        requestLimit = Integer.parseInt(getOptionalProperty(props, "requestLimit", "0"));
        requestLimitInBytes = Integer.parseInt(getOptionalProperty(props, "requestLimitInBytes", "0"));
        timeoutRequestLimit = Integer.parseInt(getOptionalProperty(props, "timeoutRequestLimit", "0"));
        requestLimitWhitelistUsers = Arrays.asList(getOptionalProperty(props, "requestLimitWhitelistUsers", "").split(",\\s*"));
        requestLimitWhitelistLimit = Integer.parseInt(getOptionalProperty(props, "requestLimitWhitelistLimit", "0"));
        pipelineCaching = Boolean.parseBoolean(getOptionalProperty(props, "pipelineCaching", "false").trim());
        pipelinePrewarming = Boolean.parseBoolean(getOptionalProperty(props, "pipelinePrewarming", "false").trim());
        maxPipelinePoolSize = Integer.parseInt(getOptionalProperty(props, "maxPipelinePoolSize", "5"));
        pipelineExpireTime = Integer.parseInt(getOptionalProperty(props, "pipelineExpireTimeInSeconds", "10"));
        requestLimitPeriodInSeconds = Integer.parseInt(getOptionalProperty(props, "requestLimitPeriodInSeconds", "0"));
        ipFingerprintFactor = Integer.parseInt(getOptionalProperty(props, "ipFingerprintFactor", "1"));
        trustXForwardForHeader = Boolean.valueOf(getOptionalProperty(props, "trustXForwardForHeader", "false").trim());
        maxWorkQueueSize = Integer.parseInt(getOptionalProperty(props, "maxWorkQueueSize", "0"));
        if (maxWorkQueueSize < 0) {
          throw new IllegalArgumentException("maxWorkQueueSize must be >= 0: " + maxWorkQueueSize);
        }
        minPort = Integer.parseInt(getOptionalProperty(props, "minPort", "0"));
        maxPort = Integer.parseInt(getOptionalProperty(props, "maxPort", "0"));
        String url = getOptionalProperty(props, "serverURL", null);
        setServerURL(url);
        String ruleIdToConfidence = getOptionalProperty(props, "ruleIdToConfidenceFile", null);
        if (ruleIdToConfidence != null) {
          ruleIdToConfidenceFile = new File(ruleIdToConfidence);
        }
        String langModel = getOptionalProperty(props, "languageModel", null);
        if (langModel != null && loadLangModel) {
          setLanguageModelDirectory(langModel);
        }
        String fasttextModel = getOptionalProperty(props, "fasttextModel", null);
        String fasttextBinary = getOptionalProperty(props, "fasttextBinary", null);
        if (fasttextBinary != null && fasttextModel != null) {
          setFasttextPaths(fasttextModel, fasttextBinary);
        }

View on GitHub (pinned to 2e990059ce)

Solutions

1. Set maxWorkQueueSize to 0 (unbounded) or a positive integer in the properties file
2. Remove the property to fall back to the default (0)
3. Double-check generated/templated config values for negative numbers

Example fix

# before (server.properties)
maxWorkQueueSize=-1
# after
maxWorkQueueSize=100

// validate before handing props to the server
int v = Integer.parseInt(props.getProperty("maxWorkQueueSize", "0"));
if (v < 0) throw new IllegalArgumentException("maxWorkQueueSize must be >= 0, got " + v);

try { cfg = new HTTPServerConfig(props, args); } catch (IllegalArgumentException e) {
  if (e.getMessage().startsWith("maxWorkQueueSize")) { props.setProperty("maxWorkQueueSize", "0"); cfg = new HTTPServerConfig(props, args); } else throw e;
}

When it happens

Trigger: Setting 'maxWorkQueueSize' to a negative integer (e.g. -1) in the properties file passed via --config.

Common situations: Hand-editing properties with sign errors; templating/config-generation bugs injecting negative values; misunderstanding that only >=0 is valid.

Understand the failure class

Background: "Invalid value" and "allowed values are" config errors: what your library rejected and how to fix it — this error's family across 41 libraries.

Related errors

• Invalid value for maxCheckThreads, must be >= 1:
• Invalid value for maxTextCheckerThreads, must be >= 1:
• Invalid value for textCheckerQueueSize, must be >= 1:
• No rules are active. Please make sure your rule ids (<option
• suppressMisspelledMatch must be a valid regex

AI-assisted analysis of languagetool-org/languagetool@2e990059ce (2026-09-06). Data as JSON: /api/errors/46c646e5bc0004b8. Report an issue: GitHub.