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), 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 codestatus— HTTP status code (matching the response status)title— short, human-readable summarydetail— human-readable explanation specific to this occurrenceinstance— 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
curl -s --compressed -H "Accept: application/json" -A "TestAgent/1.0" -H "Accept-Encoding: gzip, deflate" "<YOUR_DOMAIN>/cdn-cgi/error/1015" | jq .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:
Source: Cloudflare
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