alibaba/nacos · critical · IllegalArgumentException

[http-client] invalid connect timeout:{}

Error message

[http-client] invalid connect timeout:{}

What it means

Thrown during static initialization of ParamUtil when the NACOS.CONNECT.TIMEOUT property is set to a non-integer value (IllegalArgumentException). ParamUtil reads the timeout from NacosClientProperties, parses it with Integer.parseInt, and fails fast if the value is not a valid integer. This is a JVM-startup-time error — the exception propagates from the static initializer, causing the ParamUtil class to fail initialization.

Source

Thrown at client/src/main/java/com/alibaba/nacos/client/utils/ParamUtil.java:72

        LOGGER.info("[settings] [http-client] connect timeout:{}", connectTimeout);
        
        readTimeout = initReadTimeout();
        LOGGER.info("[settings] [http-client] read timeout:{}", readTimeout);
        
        perTaskConfigSize = initPerTaskConfigSize();
        LOGGER.info("PER_TASK_CONFIG_SIZE: {}", perTaskConfigSize);
    }
    
    private static int initConnectionTimeout() {
        String tmp = DEFAULT_NACOS_CONNECT_TIMEOUT;
        try {
            tmp = NacosClientProperties.PROTOTYPE.getProperty(NACOS_CONNECT_TIMEOUT_KEY,
                DEFAULT_NACOS_CONNECT_TIMEOUT);
            return Integer.parseInt(tmp);
        } catch (NumberFormatException e) {
            final String msg = "[http-client] invalid connect timeout:" + tmp;
            LOGGER.error("[settings] " + msg, e);
            throw new IllegalArgumentException(msg, e);
        }
    }
    
    private static int initReadTimeout() {
        String tmp = DEFAULT_NACOS_READ_TIMEOUT;
        try {
            tmp = NacosClientProperties.PROTOTYPE.getProperty(NACOS_READ_TIMEOUT_KEY,
                DEFAULT_NACOS_READ_TIMEOUT);
            return Integer.parseInt(tmp);
        } catch (NumberFormatException e) {
            final String msg = "[http-client] invalid read timeout:" + tmp;
            LOGGER.error("[settings] " + msg, e);
            throw new IllegalArgumentException(msg, e);
        }
    }
    
    private static double initPerTaskConfigSize() {
        try {

View on GitHub (pinned to 9b989acdf1)

Solutions

1. Set NACOS.CONNECT.TIMEOUT to a plain integer (milliseconds), e.g., -DNACOS.CONNECT.TIMEOUT=2000.
2. Remove the property entirely to use the default (1000ms).
3. Check all property sources (system properties, environment variables, nacos-client.properties file) for an incorrect NACOS.CONNECT.TIMEOUT value.

Example fix

# before
-DNACOS.CONNECT.TIMEOUT=2s

# after
-DNACOS.CONNECT.TIMEOUT=2000

// Validate before JVM startup — check all property sources
String timeout = System.getProperty("NACOS.CONNECT.TIMEOUT");
if (timeout != null) {
    try {
        Integer.parseInt(timeout);
    } catch (NumberFormatException e) {
        throw new IllegalArgumentException(
            "NACOS.CONNECT.TIMEOUT must be an integer (milliseconds), got: " + timeout);
    }
}

// This error occurs during class static initialization and cannot be
// caught at the call site — it fails the ParamUtil class load.
// Fix the property value before starting the JVM.
// No runtime try-catch is effective here.

When it happens

Trigger: Setting the system property or environment variable NACOS.CONNECT.TIMEOUT to a non-numeric string (e.g., 'abc', '1s', ''). The default value '1000' is used if the property is absent, so this only fires when an explicit invalid value is provided.

Common situations: Misconfigured JVM system property (-DNACOS.CONNECT.TIMEOUT=2s with a unit suffix); environment variable with a typo or wrong format; a properties file with an incorrect timeout value; copy-paste from documentation that includes units.

Understand the failure class

• Timeouts: ETIMEDOUT, deadlines, and hung requests — what actually expires when a request times out.

Related errors

• worker Id can't be greater than %d or less than 0, current w
• Illegal Raft system parameters => ReadOnlyOption : [{val}],
• 10000
• PARAMETER_MISSING
• request timeout after {timeout} milliseconds, requestId={req

AI-assisted analysis of alibaba/nacos@9b989acdf1 (2026-08-14). Data as JSON: /api/errors/f09f39741debc128. Report an issue: GitHub.