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H
http-510
Moderate
HTTP API · API Responses
HTTP 510 Not Extended indicates required protocol extension missing for this API request path.
Quick Answer
Error code HTTP-510 on your HTTP API API Responses means: HTTP 510 Not Extended indicates required protocol extension missing for this API request path.. This is usually fixable — see the step-by-step guide below.
Affected Models
Applies to all models
DOTNET-HTTPCLIENTBROWSER-FETCHGO-NET-HTTPJAVA-OKHTTPNODE-FETCHPHP-GUZZLEPY-REQUESTSRUBY-NETHTTP
Likely Causes
  1. The endpoint returned 510 because required protocol extension missing.
  2. Server-side dependency, gateway, or runtime condition failed while handling an otherwise valid request.
  3. Current retry/validation strategy does not fully account for HTTP 510 behavior in this workflow.
How to Fix It
1
Inspect API logs/traces for HTTP 510 with full request/response metadata.
2
Validate request construction against endpoint spec focusing on: required protocol extension missing.
3
Check upstream dependency health, timeout budgets, and recent deploy changes.
4
Add explicit handling path for HTTP 510 in SDK/service code.
5
Run regression tests to confirm HTTP 510 no longer appears unexpectedly.
Pro Tip
This fix requires some technical knowledge. If you're unsure about any step, consider contacting support or a qualified technician.
Related Error Codes
HTTP-400HTTP-401HTTP-402HTTP-403HTTP-404
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