apache/flink · error · IllegalArgumentException

Could not parse value for key '%s'.

Error message

Could not parse value for key '%s'.

What it means

Configuration.getOptional(option) converts the raw value to the option's type; if conversion throws, Flink reports a parse error. This variant (without the value echoed) is used when the option key is considered SENSITIVE — GlobalConfiguration.isSensitive(key, additionalSensitiveKeys) matched (e.g. keys containing 'password', 'secret', 'token', or listed in security.additional-sensitive-keys) — so the raw value is deliberately omitted from the message to avoid leaking credentials into logs.

Source

Thrown at flink-core/src/main/java/org/apache/flink/configuration/Configuration.java:378

     */
    @PublicEvolving
    public <T> T get(ConfigOption<T> configOption, T overrideDefault) {
        return getOptional(configOption).orElse(overrideDefault);
    }

    @Override
    public <T> Optional<T> getOptional(ConfigOption<T> option) {
        Optional<Object> rawValue = getRawValueFromOption(option);
        Class<?> clazz = option.getClazz();

        try {
            if (option.isList()) {
                return rawValue.map(v -> ConfigurationUtils.convertToList(v, clazz));
            } else {
                return rawValue.map(v -> ConfigurationUtils.convertValue(v, clazz));
            }
        } catch (Exception e) {
            throw new IllegalArgumentException(
                    GlobalConfiguration.isSensitive(
                                    option.key(),
                                    this.get(SecurityOptions.ADDITIONAL_SENSITIVE_KEYS))
                            ? String.format("Could not parse value for key '%s'.", option.key())
                            : String.format(
                                    "Could not parse value '%s' for key '%s'.",
                                    rawValue.map(Object::toString).orElse(""), option.key()),
                    e);
        }
    }

    @Override
    public <T> Configuration set(ConfigOption<T> option, T value) {
        final boolean canBePrefixMap = canBePrefixMap(option);
        setValueInternal(option.key(), value, canBePrefixMap);
        return this;
    }

View on GitHub (pinned to 2f3c205e92)

Solutions

1. Fix the value's syntax: durations as '10 s'/'60 s'/ISO-8601, memory as '1 gb', numbers plain; check the option's declared type.
2. Check for stray quotes/whitespace introduced by YAML formatting around the sensitive value.
3. If you genuinely need the value echoed for debugging, temporarily read it via conf.getString on a non-sensitive alias or check the file directly — never commit the fix with the secret printed.
4. For custom options, avoid sensitive-sounding key names unless the value really is secret.

Example fix

# before
metrics.reporter.prom.token.duration: 10 secondz  # unparseable duration

# after
metrics.reporter.prom.token.duration: 10 s

// Validate syntax before getOptional for duration-like options:
static boolean validDuration(String v) {
    return v == null || v.matches("(\\d+(\\.\\d+)?\\s*(ns|ms|s|min|min|h|d)\\s*)+|P.*");
}

When it happens

Trigger: A sensitive option (password/secret/token-like key) whose configured value cannot be parsed into the option's type: a malformed duration ('10 secondz'), malformed memory size ('1gbx'), non-numeric string for an int option, or bad list syntax.

Common situations: Typing a wrong unit in 'security.ssl.keystore-password'-adjacent duration/size options; copy-pasting a value with trailing whitespace or quotes into flink-conf.yaml for a typed sensitive option; a custom option named like a secret but declared with a non-string type.

Related errors

• Could not parse value '%s' for key '%s'.
• Could not register security manager due to no permission to
• Not allowed configuration change(s) were detected:\n - {erro
• Artifact fetching from raw HTTP endpoints are disabled. Set
• Configuration cannot evaluate value %s as a byte[] value

AI-assisted analysis of apache/flink@2f3c205e92 (2026-08-14). Data as JSON: /api/errors/36993e1b72a48ecd. Report an issue: GitHub.