languagetool-org/languagetool · error · IllegalArgumentException

The AfterTheDeadline mode is not supported anymore in Langua

Error message

The AfterTheDeadline mode is not supported anymore in LanguageTool 3.8 or later

What it means

LanguageTool's HTTP server once supported running in 'AfterTheDeadline' compatibility mode (set via the 'mode' property). This mode was removed in LanguageTool 3.8, and the server configuration now explicitly rejects it with this IllegalArgumentException to fail fast instead of silently misbehaving.

Source

Thrown at languagetool-server/src/main/java/org/languagetool/server/HTTPServerConfig.java:378

          setFasttextPaths(fasttextModel, fasttextBinary);
        }
        maxCheckThreads = Integer.parseInt(getOptionalProperty(props, "maxCheckThreads", "10"));
        if (maxCheckThreads < 1) {
          throw new IllegalArgumentException("Invalid value for maxCheckThreads, must be >= 1: " + maxCheckThreads);
        }
        // default value 0 = use maxCheckThreads setting (for compatibility)
        maxTextCheckerThreads = Integer.parseInt(getOptionalProperty(props, "maxTextCheckerThreads", "0"));
        if (maxTextCheckerThreads < 0) {
          throw new IllegalArgumentException("Invalid value for maxTextCheckerThreads, must be >= 1: " + maxTextCheckerThreads);
        }
        textCheckerQueueSize = Integer.parseInt(getOptionalProperty(props, "textCheckerQueueSize", "8"));
        if (textCheckerQueueSize < 0) {
          throw new IllegalArgumentException("Invalid value for textCheckerQueueSize, must be >= 1: " + textCheckerQueueSize);
        }

        boolean atdMode = getOptionalProperty(props, "mode", "LanguageTool").equalsIgnoreCase("AfterTheDeadline");
        if (atdMode) {
          throw new IllegalArgumentException("The AfterTheDeadline mode is not supported anymore in LanguageTool 3.8 or later");
        }
        String rulesConfigFilePath = getOptionalProperty(props, "rulesFile", null);
        if (rulesConfigFilePath != null) {
          rulesConfigFile = new File(rulesConfigFilePath);
          if (!rulesConfigFile.exists() || !rulesConfigFile.isFile()) {
            throw new RuntimeException("Rules Configuration file cannot be found: " + rulesConfigFile);
          }
        }
        String remoteRulesConfigFilePath = getOptionalProperty(props, "remoteRulesFile", null);
        if (remoteRulesConfigFilePath != null) {
          remoteRulesConfigFile = new File(remoteRulesConfigFilePath);
          if (!remoteRulesConfigFile.exists() || !remoteRulesConfigFile.isFile()) {
            throw new RuntimeException("Remote rules configuration file cannot be found: " + remoteRulesConfigFile);
          }
        }
        cacheSize = Integer.parseInt(getOptionalProperty(props, "cacheSize", "0"));
        if (cacheSize < 0) {
          throw new IllegalArgumentException("Invalid value for cacheSize: " + cacheSize + ", use 0 to deactivate cache");

View on GitHub (pinned to 2e990059ce)

Solutions

1. Remove the 'mode=AfterTheDeadline' line from the server properties file (default mode 'LanguageTool' needs no explicit setting)
2. Upgrade any client integration that relied on the AfterTheDeadline XML API to LanguageTool's native HTTP JSON API
3. Pin to LanguageTool <= 3.7 only if ATD compatibility is absolutely mandatory (not recommended, no security fixes)

Example fix

// before (server.properties)
mode=AfterTheDeadline

// after (server.properties)
# line removed - only 'LanguageTool' mode is supported

Properties props = loadProps();
if ("AfterTheDeadline".equalsIgnoreCase(props.getProperty("mode", "LanguageTool"))) {
    throw new IllegalStateException("mode=AfterTheDeadline is unsupported since LT 3.8; remove the 'mode' property");
}

try {
    serverConfig = new HTTPServerConfig(props);
} catch (IllegalArgumentException e) {
    if (e.getMessage().contains("AfterTheDeadline")) {
        props.remove("mode");
        serverConfig = new HTTPServerConfig(props);
    } else { throw e; }
}

When it happens

Trigger: Starting the LanguageTool HTTP server with a properties/config file (or server.properties) that contains 'mode=AfterTheDeadline'. HTTPServerConfig constructor reads the 'mode' property, compares it case-insensitively to 'AfterTheDeadline', and throws.

Common situations: Old server.properties files carried over from LanguageTool 3.7 or earlier deployments; Docker images or startup scripts with legacy config; tutorials or blog posts referencing the old ATD mode.

Understand the failure class

Background: "is deprecated and will be removed" — deprecation warnings for old API names, keywords, and options, and how to migrate before the removal release — this error's family across 29 libraries.

Related errors

• Rules Configuration file cannot be found:
• Remote rules configuration file cannot be found:
• Invalid value for cacheSize: , use 0 to deactivate cache
• Use of cacheTTLSeconds without also setting cacheSize has no
• Cannot use premiumOnly=true with non-premium version

AI-assisted analysis of languagetool-org/languagetool@2e990059ce (2026-09-06). Data as JSON: /api/errors/74814a17239ec776. Report an issue: GitHub.