linera-io/linera-protocol · error · NodeError

Unexpected certificate value

Error message

Unexpected certificate value

What it means

Raised in RemoteNode::download_certificates_by_heights while validating the batch a validator returned for a download_certificates_by_heights(chain_id, heights) call: every certificate whose inner chain_id differs from the requested chain_id triggers this error. It is a response-integrity check — a well-behaved validator must only return certificates of the chain that was asked for.

Source

Thrown at linera-core/src/remote_node.rs:261

        &self,
        chain_id: ChainId,
        heights: Vec<BlockHeight>,
    ) -> Result<Vec<ConfirmedBlockCertificate>, NodeError> {
        let mut expected_heights = VecDeque::from(heights.clone());
        let certificates = self
            .node
            .download_certificates_by_heights(chain_id, heights)
            .await?;

        if certificates.len() > expected_heights.len() {
            return Err(NodeError::TooManyCertificatesReturned {
                chain_id,
                remote_node: Box::new(self.public_key),
            });
        }

        for certificate in &certificates {
            ensure!(
                certificate.inner().chain_id() == chain_id,
                NodeError::UnexpectedCertificateValue
            );
            if let Some(expected_height) = expected_heights.pop_front() {
                ensure!(
                    expected_height == certificate.inner().height(),
                    NodeError::UnexpectedCertificateValue
                );
            } else {
                return Err(NodeError::UnexpectedCertificateValue);
            }
        }

        ensure!(
            expected_heights.is_empty(),
            NodeError::MissingCertificatesByHeights {
                chain_id,
                heights: expected_heights.into_iter().collect(),

View on GitHub (pinned to 6c226ddcb3)

Solutions

1. Exclude the offending validator from the download and retry with the remaining ones
2. Check the validator's and any proxy's configuration for cross-chain response mixing
3. Verify the requested chain_id and heights are what you intended (copy/paste mistakes make legitimate responses look wrong)
4. Report the validator if it reproducibly returns foreign certificates

fn is_unexpected_certificate_value(err: &NodeError) -> bool {
    matches!(err, NodeError::UnexpectedCertificateValue)
}

for node in validator_nodes {
    match remote_node.download_certificates_by_heights(chain_id, heights.clone()).await {
        Ok(certs) => return Ok(certs),
        Err(NodeError::UnexpectedCertificateValue) => continue, // skip bad validator
        Err(e) => return Err(e.into()),
    }
}
return Err(NodeError::UnexpectedCertificateValue.into());

When it happens

Trigger: Validator (or proxy) returns certificates belonging to another chain; corrupted deserialization routing responses between tenants; byzantine validator serving unrelated data. Only bites per-validator responses inspected directly; the client's scheduler hedges across validators and can drop a bad source.

Common situations: Shared validator infrastructure mixing responses across chains after a misconfiguration; a stale proxy cache serving another chain's certificates; adversarial testing of validator honesty.

Understand the failure class

• SSL/TLS and certificate errors — how TLS handshakes and certificate validation fail.

Related errors

• Failed to download certificates and update local node to the
• The received chain info response is invalid
• Missing certificates for chain {chain_id} in heights {height
• Node returned a BlobsNotFound error with an empty list of mi
• Local error handling validator response: validator still rep

AI-assisted analysis of linera-io/linera-protocol@6c226ddcb3 (2026-08-22). Data as JSON: /api/errors/f44b572ec07a118a. Report an issue: GitHub.