aeron-io/aeron · error · AeronException

SM has longer application specific feedback (

Error message

SM has longer application specific feedback (

What it means

StatusMessageFlyweight.groupTag() returns the group tag (a 8-byte value) from a status message but throws AeronException when the frame length indicates application-specific feedback longer than the single group tag field, i.e. the SM carries extra feedback bytes this accessor cannot safely interpret. It is a guard so callers of matchesTag do not silently misread longer feedback payloads.

Solutions

1. Check frameLength() <= StatusMessageFlyweight.HEADER_LENGTH + SIZE_OF_LONG before calling groupTag
2. Catch AeronException around matchesTag/groupTag when parsing untrusted or cross-version SM frames
3. Align Aeron versions with the peer so SM feedback lengths match expectations

Example fix

// before
if (sm.matchesTag(tag)) { ... }
// after
if (sm.frameLength() <= StatusMessageFlyweight.HEADER_LENGTH + SIZE_OF_LONG && sm.matchesTag(tag))
{
    ...
}

boolean safeForGroupTag = sm.frameLength() <= StatusMessageFlyweight.HEADER_LENGTH + SIZE_OF_LONG;

boolean hasSimpleGroupTag(StatusMessageFlyweight sm) { return sm.frameLength() <= StatusMessageFlyweight.HEADER_LENGTH + SIZE_OF_LONG; }

try { long tag = sm.groupTag(); }
catch (AeronException e) { /* SM carries extended feedback; skip or parse manually */ }

When it happens

Trigger: Calling groupTag() (directly or via matchesTag) on a StatusMessageFlyweight whose frameLength() exceeds HEADER_LENGTH + SIZE_OF_LONG, meaning the SM's application-specific feedback is longer than 8 bytes.

Common situations: Interoperating with an Aeron peer/driver that appends additional feedback data to status messages; treating a generic SM with extended feedback as a simple tagged SM.

Related errors

• unexpected response: code=
• unknown RES_TYPE=
• Insufficient length:
• expected schemaId= , actual=
• expected schemaId= , actual=

AI-assisted analysis of aeron-io/aeron@6d60124e15 (2026-09-12). Data as JSON: /api/errors/6fe84c6271def04d. Report an issue: GitHub.

Appendix: source

Thrown at aeron-client/src/main/java/io/aeron/protocol/StatusMessageFlyweight.java:277

    public int asfLength()
    {
        return (frameLength() - HEADER_LENGTH);
    }

    /**
     * The group tag (if present) from the Status Message.
     *
     * @return the group tag value or 0 if not present.
     */
    public long groupTag()
    {
        final int frameLength = frameLength();

        if (frameLength > HEADER_LENGTH)
        {
            if (frameLength > (HEADER_LENGTH + SIZE_OF_LONG))
            {
                throw new AeronException(
                    "SM has longer application specific feedback (" + (frameLength - HEADER_LENGTH) + ") than gtag");
            }

            return getLongUnaligned(GROUP_TAG_FIELD_OFFSET);
        }

        return 0;
    }

    /**
     * Set the Receiver Group Tag for the Status Message.
     *
     * @param groupTag value to set if not null.
     * @return this for a fluent API.
     */
    public StatusMessageFlyweight groupTag(final Long groupTag)
    {
        if (null != groupTag)

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