---
title: "Error reference: Format and schema | KYA"
url: https://knowyouragent.ch/en/method/errors/format
lang: en
updated: 2026-10-12
license: © Innopulse Consulting GmbH
---

# Error reference: Format and schema

Is the format recognized, are required fields present, is the version supported?

The first check establishes what was entered: a token, an evidence pack, a receipt chain, a timestamp or a signed HTTP request. It checks whether the structure is readable and whether the format's required claims are present. If this check fails, all further checks cannot work meaningfully and report their prerequisite as not met.

Most codes in this check arise when copying: truncated tokens, extra characters or swapped input fields.

## `format_unknown`

**The format is not known.**

**Cause:** The input matches no format the engine knows, for example because extra text, quotation marks or an entirely different document was pasted.

**Fix:** Paste only the evidence itself, without explanatory text. Supported are SD-JWT VC, JWS, kya-pack/1, kya-chain/1, status lists, RFC 3161 timestamps, Verifiable Intent and HTTP signatures.

## `format_recognized_not_supported`

**The format is recognized but not checked in this version.**

**Cause:** The format is known but deliberately not verified in this version, for example classic AP2 mandates in JSON format or encrypted tokens.

**Fix:** Use a supported format, for example the AP2 chain converged with Verifiable Intent. The certificate states explicitly that nothing was verified, instead of failing silently.

## `not_evidence_key_material`

**This is key material, not evidence. Paste it under “Trust of the verifying party”.**

**Cause:** Key material was pasted, such as a JWK, a JWKS or a PEM certificate, rather than evidence.

**Fix:** Paste keys under “Trust of the verifying party”: public keys as JWK or JWKS, certificates of timestamp authorities as PEM. The input field is for the evidence.

## `malformed`

**The input is structurally defective.**

**Cause:** The structure is damaged: Base64 cannot be decoded, JSON is invalid or parts are missing. Often the evidence was truncated when copying or altered by line breaks.

**Fix:** Copy the evidence again, completely and unchanged. The JWT decoder and SD-JWT decoder tools show which part is not readable.

## `required_claim_missing`

**A required field is missing.**

**Cause:** A claim required by the format is missing, such as the issuer, the type, the binding to a key or a point in time.

**Fix:** The issuer must issue the evidence according to the verification profile. Check the evidence against the published JSON schemas and add the missing claim at issuance.

## `format_not_supported`

**Not checked because the format is not supported.**

**Cause:** The variant of the format is not supported, for example an unknown version of an evidence pack or an unknown type.

**Fix:** Create the evidence in a supported version. The verification profile and the versions page state which versions apply.

[Error reference](https://knowyouragent.ch/en/method/errors) · [Checks](https://knowyouragent.ch/en/method/checks)

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Quelle: https://knowyouragent.ch/en/method/errors/format · KYA – Know Your Agent