aeron-io/aeron · error · IllegalArgumentException

Unknown address type

Error message

Unknown address type:{simpleName}

What it means

PublicationErrorFrameFlyweight.sourceAddress(InetSocketAddress) only knows how to encode Inet4Address and Inet6Address instances into the error frame. If the passed socket address wraps any other InetAddress subclass (or null-like variant), it throws IllegalArgumentException.

Solutions

1. Resolve the hostname before calling sourceAddress: ensure address.getAddress() is non-null and is Inet4Address or Inet6Address.
2. Use InetAddress.getByName(host) or InetSocketAddress with a resolvable host so a standard IPv4/IPv6 address is produced.
3. Normalize loopback/any addresses via InetAddress.getLoopbackAddress() or InetAddress.getByAddress(new byte[4]) before encoding.
4. Reject or skip error frames whose source address cannot be resolved to a plain IP.

Example fix

// before
flyweight.sourceAddress(new InetSocketAddress(host, port)); // unresolved -> non-IP
// after
InetAddress addr = InetAddress.getByName(host); // resolves to Inet4/6
flyweight.sourceAddress(new InetSocketAddress(addr, port));

InetAddress addr = socketAddress.getAddress();
if (!(addr instanceof Inet4Address) && !(addr instanceof Inet6Address)) {
    throw new IllegalArgumentException("address must be resolved IPv4/IPv6: " + socketAddress);
}

static boolean isEncodableAddress(InetSocketAddress a) {
    return a != null && !a.isUnresolved()
        && (a.getAddress() instanceof Inet4Address || a.getAddress() instanceof Inet6Address);
}

try { flyweight.sourceAddress(socketAddress); } catch (IllegalArgumentException e) { log.warn("Skipping error frame with non-IP source address", e); }

When it happens

Trigger: Calling sourceAddress() with an InetSocketAddress whose address is not Inet4Address or Inet6Address — typically from a socket bound to a custom InetAddress subclass, a loopback/any-address produced unusually, or programmatic construction of an address object that isn't a standard IP address.

Common situations: Using a proxy/socket library that returns custom InetAddress subclasses; building InetSocketAddress from an unresolved hostname (address is null/InetSocketAddress is unresolved); tests that fabricate InetAddress subclasses.

Understand the failure class

Background: "Must be a positive integer", "Invalid value", "Unsupported": the invalid-argument-value error family, when a library rejects the value you pass — this error's family across 35 libraries.

Related errors

• Unknown address type
• could not re-resolve: control=
• could not re-resolve: endpoint=
• could not resolve control address:
• could not resolve endpoint address:

AI-assisted analysis of aeron-io/aeron@6d60124e15 (2026-09-12). Data as JSON: /api/errors/0a04765243e53535. Report an issue: GitHub.

Appendix: source

Thrown at aeron-client/src/main/java/io/aeron/command/PublicationErrorFrameFlyweight.java:275

    {
        final short sourcePort = (short)(sourceAddress.getPort() & 0xFFFF);
        final InetAddress address = sourceAddress.getAddress();

        buffer.putShort(offset + ADDRESS_PORT_OFFSET, sourcePort);
        buffer.putBytes(offset + ADDRESS_OFFSET, address.getAddress());
        if (address instanceof Inet4Address)
        {
            buffer.putShort(offset + ADDRESS_TYPE_OFFSET, ADDRESS_TYPE_IPV4);
            buffer.setMemory(
                offset + ADDRESS_OFFSET + IPV4_ADDRESS_LENGTH, IPV6_ADDRESS_LENGTH - IPV4_ADDRESS_LENGTH, (byte)0);
        }
        else if (address instanceof Inet6Address)
        {
            buffer.putShort(offset + ADDRESS_TYPE_OFFSET, ADDRESS_TYPE_IPV6);
        }
        else
        {
            throw new IllegalArgumentException("Unknown address type:" + address.getClass().getSimpleName());
        }

        return this;
    }

    /**
     * Get the source address of this error frame.
     *
     * @return source address of the error frame.
     */
    public InetSocketAddress sourceAddress()
    {
        final short addressType = buffer.getShort(offset + ADDRESS_TYPE_OFFSET);
        final int port = buffer.getShort(offset + ADDRESS_PORT_OFFSET) & 0xFFFF;

        final byte[] address;
        if (ADDRESS_TYPE_IPV4 == addressType)
        {

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