What are common ARC validation failures?

Incorrect or skipped instance numbers.

Bad or missing ARC Seals.

Modified ARC Authentication Results.

Signature mismatches.

Untrusted ARC signer domains.

Expired or incorrect cryptographic keys.

Broken sealing chains where AS does not match earlier signatures.

These failures break trust in the message’s forwarding path and often result in a Chain Validation status of cv=fail.