502 Bad Gateway

generated: '2026-07-26' method: derived source: >- openapi/knight-frank-api-v3-openapi.json (which declares only "200 Success" for all eleven operations and defines no error schema) plus the failure responses actually observed on 2026-07-26 against both Knight Frank service hosts. There is no docs error reference to search — Knight Frank publishes no developer documentation. format: none rfc9457: false description: >- Knight Frank's APIs have no error contract. The published OpenAPI document declares no 4xx or 5xx response on any operation and defines no error schema, so every failure below was established by probing. Failures come back as bare status codes with empty bodies, an unstructured 500, or the framework default from ASP.NET Web API — never as a typed, documented problem object. An agent or integrator cannot distinguish "no results", "bad parameter" and "wrong parameter name" from the response shape alone. problems: - status: 200 title: Success (declared) detail: >- The only response declared in the contract, on all eleven operations, with no response schema and no content type. source_operation: openapi/knight-frank-api-v3-openapi.json (all paths) declared: true - status: 204 title: No content — silently ignored parameter observed_on: GET https://api-v3.web.prd-knightfrank.com/search?searchTerm=london body: empty cause: >- The operation expects `term`; an unrecognised parameter name is not rejected as a validation error, it simply produces an empty 204. remediation: Use the documented parameter name `term`. declared: false - status: 404 title: Not found observed_on: GET https://api-v3.web.prd-knightfrank.com/nonexistent-path-probe body: empty (zero bytes, no content-type) cause: Unknown route on the api-v3 host. declared: false - status: 500 title: Server error on missing required parameters observed_on: GET https://api-v3.web.prd-knightfrank.com/intelligencelab/facets body: unstructured cause: >- Required query parameters omitted. The service raises an unhandled server error instead of returning a 400 validation response — the contract marks no parameter as required, so a caller has no way to know which are. remediation: Supply term / languageCode / hostname; expect no validation feedback. declared: false - status: 401 title: Unauthorized (api-v2) observed_on: - GET https://api-v2.web.prd-knightfrank.com/properties/search - GET https://api-v2.web.prd-knightfrank.com/secure/account body: empty (zero bytes) www_authenticate: not returned cause: >- The property/account service requires an Azure AD B2C bearer token. No challenge header, no error body and no documentation of how a token is obtained. remediation: >- Not remediable by a third party — no developer credential exists. See authentication/knight-frank-authentication.yml. declared: false - status: 404 title: No HTTP resource was found that matches the request URI (api-v2) observed_on: GET https://api-v2.web.prd-knightfrank.com/properties body: '{"Message":"No HTTP resource was found that matches the request URI ..."}' envelope_field: Message cause: ASP.NET Web API default routing error — the framework default, not a designed error type. declared: false - status: 302 title: Redirect to a server error page observed_on: - GET https://api-v2.web.prd-knightfrank.com/ - GET https://api-v2.web.prd-knightfrank.com/swagger/v1/swagger.json body: redirect to /error.htm?aspxerrorpath=/ cause: Classic ASP.NET custom-errors redirect leaking into an API surface. declared: false - status: 502 title: Bad Gateway from the edge WAF observed_on: GET https://api.knightfrank.com/ body: '502 Bad Gateway... wswaf' cause: >- api.knightfrank.com is CNAMEd to a Gcore edge with a WAF in front of no published origin. It is not a developer surface; repeated requests are dropped at the connection level. declared: false gaps: - No error is declared in the OpenAPI document at all. - No error code registry, no error type URIs, no machine-readable error taxonomy. - No RFC 9457 application/problem+json. - No 400 validation responses — bad input produces 204, 500 or silence. - No 429 and no rate-limit contract.