---
description: "Cloudflare-generated 1xxx errors now return structured JSON when requested with 'Accept: application/json' or 'Accept: application/problem+json', following RFC 9457 (Problem Details for HTTP APIs)."
title: JSON responses and RFC 9457 support for Cloudflare 1xxx errors
image: https://developers.cloudflare.com/changelog/post/2026-03-11-json-rfc9457-responses-for-1xxx-errors/og.png?v=81b72a3d53a93d12
---

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March 11, 2026

## JSON responses and RFC 9457 support for Cloudflare 1xxx errors

[Cloudflare Fundamentals](https://developers.cloudflare.com/fundamentals/)

Copy as Markdown| [View as Markdown](https://developers.cloudflare.com/changelog/post/2026-03-11-json-rfc9457-responses-for-1xxx-errors/index.md)| [Agent setup](https://developers.cloudflare.com/agent-setup/)

Cloudflare-generated 1xxx errors now return structured JSON when clients send `Accept: application/json` or `Accept: application/problem+json`. JSON responses follow [RFC 9457 (Problem Details for HTTP APIs) ↗︎](https://www.rfc-editor.org/rfc/rfc9457), so any HTTP client that understands Problem Details can parse the base members without Cloudflare-specific code.

#### Breaking change

The Markdown frontmatter field `http_status` has been renamed to `status`. Agents consuming Markdown frontmatter should update parsers accordingly.

#### Changes

**JSON format.** Clients sending `Accept: application/json` or `Accept: application/problem+json` now receive a structured JSON object with the same operational fields as Markdown frontmatter, plus RFC 9457 standard members.

**RFC 9457 standard members (JSON only):**

- `type` — URI pointing to Cloudflare documentation for the specific error code
- `status` — HTTP status code (matching the response status)
- `title` — short, human-readable summary
- `detail` — human-readable explanation specific to this occurrence
- `instance` — Ray ID identifying this specific error occurrence

**Field renames:**

- `http_status` -> `status` (JSON and Markdown)
- `what_happened` -> `detail` (JSON only — Markdown prose sections are unchanged)

**Content-Type mirroring.** Clients sending `Accept: application/problem+json` receive `Content-Type: application/problem+json; charset=utf-8` back; `Accept: application/json` receives `application/json; charset=utf-8`. Same body in both cases.

#### Negotiation behavior

| Request header sent | Response format |
| --- | --- |
| `Accept: application/json` | JSON (`application/json` content type) |
| `Accept: application/problem+json` | JSON (`application/problem+json` content type) |
| `Accept: application/json, text/markdown;q=0.9` | JSON |
| `Accept: text/markdown` | Markdown |
| `Accept: text/markdown, application/json` | Markdown (equal `q`, first-listed wins) |
| `Accept: */*` | HTML (default) |

#### Availability

Available now for Cloudflare-generated 1xxx errors.

#### Get started

```bash
curl -s --compressed -H "Accept: application/json" -A "TestAgent/1.0" -H "Accept-Encoding: gzip, deflate" "<YOUR_DOMAIN>/cdn-cgi/error/1015" | jq .
```

```bash
curl -s --compressed -H "Accept: application/problem+json" -A "TestAgent/1.0" -H "Accept-Encoding: gzip, deflate" "<YOUR_DOMAIN>/cdn-cgi/error/1015" | jq .
```

References:

- [RFC 9457 — Problem Details for HTTP APIs ↗︎](https://www.rfc-editor.org/rfc/rfc9457)
- [Cloudflare 1xxx error documentation](https://developers.cloudflare.com/support/troubleshooting/http-status-codes/cloudflare-1xxx-errors/)

```json
{"@context":"https://schema.org","@type":"BlogPosting","@id":"https://developers.cloudflare.com/changelog/post/2026-03-11-json-rfc9457-responses-for-1xxx-errors/#page","headline":"JSON responses and RFC 9457 support for Cloudflare 1xxx errors","description":"Cloudflare-generated 1xxx errors now return structured JSON when requested with 'Accept: application/json' or 'Accept: application/problem+json', following RFC 9457 (Problem Details for HTTP APIs).","url":"https://developers.cloudflare.com/changelog/post/2026-03-11-json-rfc9457-responses-for-1xxx-errors/","inLanguage":"en","image":"https://developers.cloudflare.com/changelog/post/2026-03-11-json-rfc9457-responses-for-1xxx-errors/og.png?v=81b72a3d53a93d12","dateModified":"2026-03-11","datePublished":"2026-03-11","publisher":{"@type":"Organization","name":"Cloudflare","description":"One platform for your apps, agents, and workforce. Build, secure, and scale without managing infrastructure","url":"https://www.cloudflare.com/","sameAs":["https://github.com/cloudflare","https://www.linkedin.com/company/cloudflare","https://x.com/cloudflare"],"logo":{"@type":"ImageObject","url":"https://developers.cloudflare.com/logo.svg"},"address":{"@type":"PostalAddress","streetAddress":"101 Townsend St","addressLocality":"San Francisco","addressRegion":"CA","postalCode":"94107","addressCountry":"US"},"contactPoint":[{"@type":"ContactPoint","contactType":"Customer Support","url":"https://support.cloudflare.com/","availableLanguage":["English"]},{"@type":"ContactPoint","contactType":"Sales","url":"https://www.cloudflare.com/contact/","availableLanguage":["English"]}]},"isPartOf":{"@type":"WebSite","@id":"https://developers.cloudflare.com/#website","name":"Cloudflare Docs","url":"https://developers.cloudflare.com/"}}
```