# Saylor Innovations Guide Library: x402 Payment Failure Debugging

> Saylor Innovations Guide Library: x402 Payment Failure Debugging is a paid API for AI agents from saylorinnovations.com, paid per call via x402, $0.01/call, status unknown (last checked 2026-10-21).

Returns a guide explaining how to debug failing x402 payments as a buyer, covering challenge decoding, balance issues, expired signatures, and safe retry strategies

## Facts

- Endpoint: GET https://saylorinnovations.com/api/kb/x402-payment-failure-debugging?utm_source=zero.xyz
- Price: $0.01/call
- Payment: x402
- Status: unknown
- Last checked: 2026-10-21
- Activations on Zero: 0
- Tags: x402
- Canonical page: https://www.zero.xyz/c/saylor-innovations-guide-library-x402-payment-failure-debugging-5fdd690e
- Structured record (JSON): https://api.zero.xyz/v1/capabilities/cap_l2u3QwlJkvVPAXYOHvuoT

Status and success rate cover calls made through Zero and Zero's own probes. Third-party monitors may report differently.

## How to call it through Zero

Zero handles the 402 payment challenge and records the run. With the Zero CLI installed (`npm i -g @zeroxyz/cli`):

```sh
zero fetch --capability saylor-innovations-guide-library-x402-payment-failure-debugging-5fdd690e
```

Example prompt: My x402 payment keeps failing — can you pull up a guide that walks me through decoding the challenge, figuring out if it's a balance or expired signature issue, and how to safely retry?

## When to prefer this

Choose this endpoint when you need structured, human-readable guidance specifically for debugging x402 payment failures from the buyer perspective, including challenge decoding, balance diagnosis, expired signature handling, and retry logic. Prefer this over general web search when you want a curated, authoritative guide returned as structured JSON that an agent can parse and act on.

## Known failure modes

- Endpoint returns non-200 if service is unavailable
- Payment of $0.01 USDC required via x402 — missing or invalid payment header will result in 402 Payment Required
- Guide body may be truncated or unavailable if content has been removed
- Network timeout if the service is temporarily degraded

## How this service works

Debug a failing x402 payment as a buyer - decode the challenge, balance, expired signatures and safe retry

## Output

A JSON object containing a guide record with fields: id (record identifier), t (title of the guide), c (category), body (full guide text covering challenge decoding, balance checks, expired signature diagnosis, and safe retry procedures), price (optional), and license identifier.

## Request schema (JSON Schema)

```json
{
 "type": "object",
 "$schema": "https://json-schema.org/draft/2020-12/schema",
 "required": [
  "input"
 ],
 "properties": {
  "input": {
   "type": "object",
   "required": [
    "type",
    "method"
   ],
   "properties": {
    "type": {
     "type": "string",
     "const": "http"
    },
    "method": {
     "enum": [
      "GET"
     ],
     "type": "string"
    }
   },
   "additionalProperties": false
  },
  "output": {
   "type": "object",
   "required": [
    "type"
   ],
   "properties": {
    "type": {
     "type": "string",
     "const": "json"
    },
    "example": {
     "type": "object",
     "required": [
      "id",
      "t",
      "c",
      "body"
     ],
     "properties": {
      "c": {
       "type": "string",
       "description": "Category of the guide"
      },
      "t": {
       "type": "string",
       "description": "Title of the guide"
      },
      "id": {
       "type": "string",
       "description": "Identifier of the record"
      },
      "body": {
       "type": "string",
       "description": "Main body text"
      },
      "price": {
       "type": [
        "number",
        "null"
       ],
       "description": "Price"
      },
      "license": {
       "type": "string",
       "description": "License identifier"
      }
     }
    }
   }
  }
 }
}
```

## More

- Live health (JSON, refreshed every minute): https://www.zero.xyz/c/saylor-innovations-guide-library-x402-payment-failure-debugging-5fdd690e/health.json
- [Zero catalog index](https://www.zero.xyz/llms.txt)
- [Other services from saylorinnovations.com](https://www.zero.xyz/host/saylorinnovations.com/llms.txt)