languagetool-org/languagetool · error · IllegalArgumentException

dbLogging can only be true if dbDriver, dbUrl, dbUsername, a

Error message

dbLogging can only be true if dbDriver, dbUrl, dbUsername, and dbPassword are all set

What it means

When 'dbLogging=true' the server logs rule matches to a database, which requires complete JDBC connection settings: dbDriver, dbUrl, dbUsername, and dbPassword. If any of these is null, HTTPServerConfig throws this IllegalArgumentException because logging to the DB would fail.

Source

Thrown at languagetool-server/src/main/java/org/languagetool/server/HTTPServerConfig.java:462

        gracefulDatabaseFailure = Boolean.parseBoolean(getOptionalProperty(props, "gracefulDatabaseFailure", "false").trim());
        dbDriver = getOptionalProperty(props, "dbDriver", null);
        dbUrl = getOptionalProperty(props, "dbUrl", null);
        dbUsername = getOptionalProperty(props, "dbUsername", null);
        dbPassword = getOptionalProperty(props, "dbPassword", null);
        dbTimeoutSeconds = Integer.parseInt(getOptionalProperty(props, "dbTimeoutSeconds", "10"));
        dbMaxConnections = Integer.parseInt(getOptionalProperty(props, "dbMaxConnections", "10"));
        databaseErrorRateThreshold = Integer.parseInt(getOptionalProperty(props, "dbErrorRateThreshold", "50"));
        databaseTimeoutRateThreshold = Integer.parseInt(getOptionalProperty(props, "dbTimeoutRateThreshold", "100"));
        databaseDownIntervalSeconds = Integer.parseInt(getOptionalProperty(props, "dbDownIntervalSeconds", "10"));
        dbLogging = Boolean.valueOf(getOptionalProperty(props, "dbLogging", "false").trim());
        passwortLoginAccessListPath = getOptionalProperty(props, "passwortLoginAccessListPath", "");
        prometheusMonitoring = Boolean.valueOf(getOptionalProperty(props, "prometheusMonitoring", "false").trim());
        prometheusPort = Integer.parseInt(getOptionalProperty(props, "prometheusPort", "9301"));
        skipLoggingRuleMatches = Boolean.valueOf(getOptionalProperty(props, "skipLoggingRuleMatches", "false").trim());
        skipLoggingChecks = Boolean.valueOf(getOptionalProperty(props, "skipLoggingChecks", "false").trim());
        if (dbLogging && (dbDriver == null || dbUrl == null || dbUsername == null || dbPassword == null)) {
          throw new IllegalArgumentException("dbLogging can only be true if dbDriver, dbUrl, dbUsername, and dbPassword are all set");
        }
        slowRuleLoggingThreshold = Integer.valueOf(getOptionalProperty(props, "slowRuleLoggingThreshold", "-1"));
        disabledRuleIds = Arrays.asList(getOptionalProperty(props, "disabledRuleIds", "").split(",\\s*"));
        localApiMode = Boolean.parseBoolean(getOptionalProperty(props, "localApiMode", "false"));
        motherTongue = getOptionalProperty(props, "motherTongue", "en-US");
        String preferredLanguages = getOptionalProperty(props, "preferredLanguages", "").replace(" ", "");
        if (!preferredLanguages.equals("")) {
          this.preferredLanguages = Arrays.asList(preferredLanguages.split(","));
        }
        dictLimitUser = Integer.valueOf(getOptionalProperty(props, "dictLimitUser", "0"));
        dictLimitTeam = Integer.valueOf(getOptionalProperty(props, "dictLimitTeam", "0"));
        styleGuideLimitUser = Integer.valueOf(getOptionalProperty(props, "styleGuideLimitUser", "0"));
        styleGuideLimitTeam = Integer.valueOf(getOptionalProperty(props, "styleGuideLimitTeam", "0"));
        requestLimitAccessToken = getOptionalProperty(props, "requestLimitAccessToken", null);
        jwtSecret = getOptionalProperty(props, "jwtSecret", null);
        externalRolloutServiceUrl = getOptionalProperty(props, "externalRolloutServiceUrl", null);
        externalRolloutServiceApiKey = getOptionalProperty(props, "externalRolloutServiceApiKey", null);

View on GitHub (pinned to 2e990059ce)

Solutions

1. Set all four properties: dbDriver (e.g. com.mysql.cj.jdbc.Driver), dbUrl, dbUsername, dbPassword
2. Inject the missing values at deploy time via environment-variable substitution in the properties template
3. Set 'dbLogging=false' if database logging is not actually needed

Example fix

// before (server.properties)
dbLogging=true
dbUrl=jdbc:mysql://localhost/ltlogs

// after (server.properties)
dbLogging=true
dbDriver=com.mysql.cj.jdbc.Driver
dbUrl=jdbc:mysql://localhost/ltlogs
dbUsername=ltuser
dbPassword=secret

if (Boolean.parseBoolean(props.getProperty("dbLogging", "false"))) {
    for (String k : new String[]{"dbDriver", "dbUrl", "dbUsername", "dbPassword"}) {
        if (props.getProperty(k) == null) throw new IllegalStateException("dbLogging=true requires " + k);
    }
}

try {
    serverConfig = new HTTPServerConfig(props);
} catch (IllegalArgumentException e) {
    if (e.getMessage().startsWith("dbLogging can only be true")) {
        log.error("Incomplete DB config; check dbDriver/dbUrl/dbUsername/dbPassword");
    }
    throw e;
}

When it happens

Trigger: Server properties file contains 'dbLogging=true' but is missing one or more of dbDriver, dbUrl, dbUsername, or dbPassword.

Common situations: Credentials omitted from the config for security but not injected via environment/template; partial config copied from another environment; dbDriver/dbUrl forgotten while only user/password set.

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

• The AfterTheDeadline mode is not supported anymore in Langua
• 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

AI-assisted analysis of languagetool-org/languagetool@2e990059ce (2026-09-06). Data as JSON: /api/errors/23190562b293de00. Report an issue: GitHub.