> ## Documentation Index
> Fetch the complete documentation index at: https://docs.qedproof.site/llms.txt
> Use this file to discover all available pages before exploring further.

# Reason codes

> The reason_code values that accompany a receipt's verdict, and which verdicts they go with.

A receipt's `verdict.reason_code` explains why a verdict came out the way it did. It should be present for every
verdict except `verified`, and must be present for `unverifiable`.

| Code                       | Used with      | Meaning                                                                                       |
| -------------------------- | -------------- | --------------------------------------------------------------------------------------------- |
| `not_found`                | `failed`       | The destination was read, and no matching outcome existed by the deadline.                    |
| `content_mismatch`         | `mismatch`     | The fingerprint differs from what the claim stated.                                           |
| `target_mismatch`          | `mismatch`     | The outcome exists, but under a different target — a different account, branch, or recipient. |
| `observed_after_tolerance` | `late`         | The outcome is present and matches, but appeared after the tolerance window.                  |
| `no_connection`            | `unverifiable` | The issuer holds no access to the destination for this target.                                |
| `permission_denied`        | `unverifiable` | Access exists, but doesn't cover this read.                                                   |
| `rate_limited`             | `unverifiable` | The destination throttled every read attempt until the deadline.                              |
| `destination_unavailable`  | `unverifiable` | The destination errored or timed out until the deadline.                                      |
| `unsupported_action`       | `unverifiable` | No verifier profile exists for the claim's `action`.                                          |
| `claim_ambiguous`          | `unverifiable` | The claim lacks the fields the action's profile needs.                                        |
| `verifier_error`           | `unverifiable` | An internal failure inside the verifier.                                                      |

See [verdicts](/concepts/verdicts) for what each verdict value means, and the rules QED Proof follows when deciding
between them.