aeron-io/aeron · error · InvalidChannelException

invalid maxResend= , must be > 0 and <=

Error message

invalid maxResend=<maxResend>, must be > 0 and <= <MAX_RESEND_MAX>

What it means

The `max-resend` channel URI parameter was parsed but is outside the allowed range: it must be greater than 0 and at most Configuration.MAX_RESEND_MAX. Aeron throws InvalidChannelException because the value controls how many resends may be outstanding and an out-of-range value is unsafe.

Solutions

1. Set max-resend to a positive value within the documented cap (check Configuration.MAX_RESEND_MAX for your Aeron version)
2. Remove the max-resend parameter to use the driver default
3. Clamp the value in code before building the URI: Math.max(1, Math.min(value, MAX_RESEND_MAX))
4. If you want to disable resends, this param is not the mechanism — review the loss-control docs

Example fix

// before
"aeron:udp?endpoint=localhost:40456|max-resend=0"
// after
"aeron:udp?endpoint=localhost:40456|max-resend=6"

int maxResend = configuredMaxResend;
if (maxResend <= 0 || maxResend > io.aeron.driver.Configuration.MAX_RESEND_MAX)
    throw new IllegalArgumentException("max-resend must be > 0 and <= " + Configuration.MAX_RESEND_MAX);

try { publication = aeron.addPublication(uri, streamId); }
catch (InvalidChannelException e) {
    if (e.getMessage().contains("invalid max-resend")) {
        throw new ConfigurationException("Clamp max-resend to [1, MAX_RESEND_MAX]", e);
    } throw e;
}

When it happens

Trigger: Adding a publication with a channel URI containing `max-resend=0`, a negative value, or a value exceeding Configuration.MAX_RESEND_MAX (e.g. max-resend=100).

Common situations: Misreading the parameter semantics (setting 0 thinking 'no resends'); copying a value from docs for a different Aeron version where the cap differed; config templating generating bad values.

Understand the failure class

Background: "value must be between 0 and 1" / "out of range" / "must not be negative" errors: fixing range-validation failures across open-source libraries — this error's family across 42 libraries.

Related errors

• destinations must not contain the key
• difference greater than 2^31 - 1: termId=
• invalid control mode
• invalid media
• invalid , must be a number

AI-assisted analysis of aeron-io/aeron@6d60124e15 (2026-09-12). Data as JSON: /api/errors/675fabd9ecd0944b. Report an issue: GitHub.

Appendix: source

Thrown at aeron-driver/src/main/java/io/aeron/driver/PublicationParams.java:535

        untetheredRestingTimeoutNs = getTimeoutNs(
            channelUri, UNTETHERED_RESTING_TIMEOUT_PARAM_NAME, ctx.untetheredRestingTimeoutNs());
    }

    private void getMaxResend(final ChannelUri channelUri, final MediaDriver.Context ctx)
    {
        final String maxRetransmtsString = channelUri.get(MAX_RESEND_PARAM_NAME);

        if (maxRetransmtsString == null)
        {
            maxResend = ctx.maxResend();
        }
        else
        {
            maxResend = parseInt(maxRetransmtsString, MAX_RESEND_PARAM_NAME);

            if (maxResend <= 0 || maxResend > Configuration.MAX_RESEND_MAX)
            {
                throw new InvalidChannelException(
                    "invalid " + MAX_RESEND_PARAM_NAME + "=" + maxResend +
                    ", must be > 0 and <= " + Configuration.MAX_RESEND_MAX);
            }
        }
    }

    private static int parseInt(final String value, final String paramName)
    {
        try
        {
            return Integer.parseInt(value);
        }
        catch (final NumberFormatException ex)
        {
            throw new InvalidChannelException(
                "invalid " + paramName + ", must be a number", ex);
        }
    }

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