aeron-io/aeron · error · ArchiveException

expected schemaId=1055, actual=

Error message

expected schemaId=1055, actual=<schemaId>

What it means

RecordingSubscriptionDescriptorPoller.onFragment checks each fragment's SBE MessageHeader schemaId against MessageHeaderDecoder.SCHEMA_ID (1055) before dispatching on templateId. A mismatch means the fragment is not an Archive control-protocol message and cannot be safely decoded, so ArchiveException is thrown with the actual schemaId.

Solutions

1. Use the same aeron-archive version on archive and client so SBE schema ids match
2. Dedicate the control channel/stream to archive control traffic
3. Confirm listRecordingSubscriptions targets the correct archive control channel
4. Validate no manual offset manipulation occurs before messageHeaderDecoder.wrap

Example fix

// before: mixed versions
<dependency io.aeron:aeron-client:1.40.0> + archive 1.44.0
// after: aligned versions
<dependency io.aeron:aeron-client:1.44.0> + <dependency io.aeron:aeron-archive:1.44.0>

MessageHeaderDecoder hdr = new MessageHeaderDecoder().wrap(buffer, offset);
assert hdr.schemaId() == MessageHeaderDecoder.SCHEMA_ID : "schema mismatch: " + hdr.schemaId();

boolean isArchiveControlFragment(DirectBuffer buffer, int offset) {
    return new MessageHeaderDecoder().wrap(buffer, offset).schemaId() == MessageHeaderDecoder.SCHEMA_ID;
}

try { poller.poll(); }
catch (ArchiveException e) { if (e.getMessage().contains("schemaId")) { log.error("codec version mismatch", e); } }

When it happens

Trigger: Fragments on the control subscription used to list recording subscriptions carry a schemaId other than 1055 — codec version mismatch, foreign publisher on the control stream, or wrong stream wiring.

Common situations: Upgrading Aeron partially (client new, archive old or vice versa); reusing a control channel also used by an application publisher; custom tooling replaying foreign messages into the stream.

Understand the failure class

Background: Schema validation failed / invalid input schema: payload rejected because its shape doesn't match the expected schema — this error's family across 28 libraries.

Related errors

• expected schemaId=
• expected schemaId=1055, actual=
• expected schemaId=
• expected schemaId=
• expected schemaId=

AI-assisted analysis of aeron-io/aeron@6d60124e15 (2026-09-12). Data as JSON: /api/errors/5cdd5756b9f17bd7. Report an issue: GitHub.

Appendix: source

Thrown at aeron-archive/src/main/java/io/aeron/archive/client/RecordingSubscriptionDescriptorPoller.java:182

        this.remainingSubscriptionCount = subscriptionCount;
        isDispatchComplete = false;
    }

    @SuppressWarnings("MethodLength")
    ControlledFragmentAssembler.Action onFragment(
        final DirectBuffer buffer, final int offset, final int length, final Header header)
    {
        if (isDispatchComplete)
        {
            return ControlledFragmentAssembler.Action.ABORT;
        }

        messageHeaderDecoder.wrap(buffer, offset);

        final int schemaId = messageHeaderDecoder.schemaId();
        if (schemaId != MessageHeaderDecoder.SCHEMA_ID)
        {
            throw new ArchiveException("expected schemaId=" + MessageHeaderDecoder.SCHEMA_ID + ", actual=" + schemaId);
        }

        final int templateId = messageHeaderDecoder.templateId();
        switch (templateId)
        {
            case ControlResponseDecoder.TEMPLATE_ID:
                controlResponseDecoder.wrap(
                    buffer,
                    offset + MessageHeaderEncoder.ENCODED_LENGTH,
                    messageHeaderDecoder.blockLength(),
                    messageHeaderDecoder.version());

                if (controlResponseDecoder.controlSessionId() == controlSessionId)
                {
                    final ControlResponseCode code = controlResponseDecoder.code();
                    final long responseCorrelationId = controlResponseDecoder.correlationId();

                    if (ControlResponseCode.SUBSCRIPTION_UNKNOWN == code && responseCorrelationId == correlationId)

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