Membrane API Gateway Error Reference

Membrane API Gateway reports errors as Problem Details (RFC 9457). In development mode, the error response contains a see field that links to one of the pages below. Each page explains what the error means, what usually causes it and how to fix it.

How to Read an Error Response

{
  "type": "https://membrane-api.io/problems/user",
  "title": "Invalid path or method",
  "status": 404,
  "detail": "The requested path or HTTP method is not supported.",
  "see": "https://membrane-api.io/problems/user/routing"
}

{
  "type": "https://membrane-api.io/problems/user",
  "title": "Invalid path or method",
  "status": 404,
  "detail": "The requested path or HTTP method is not supported.",
  "see": "https://membrane-api.io/problems/user/routing"
}

The type names the category of the error: user, security, gateway, internal or operation-error. The see link points to the page for that specific error. In production mode, see and most details are left out of the response.

User Errors

The request or the gateway configuration caused the problem. These errors usually have a 4xx status.

Error	Path
400 Could Not Create Thumbprint	`user/acme-http-challenge`
GraphQL Protection Violation	`user/graphql-protection`
400 Could Not Generate XML From HTTP	`user/http-2-xml`
400 Malformed Request Path or Host	`user/http-client/malformed-url`
400 Invalid Request Framing	`user/http-server-handler/invalid-framing`
409 Idempotency Key Already Processed	`user/idempotency`
400 Invalid Character in Request Path	`user/invalid-path`
400 JSON Protection Violation	`user/json-protection`
404 No Matching API Found	`user/openapi/not-found`
404 OpenAPI Document Not Found	`user/openapi/openapi-publisher/wrong-id`
400 Error During OpenAPI Request Validation	`user/openapi/request/generic`
500 Error During OpenAPI Response Validation	`user/openapi/response/generic`
400 Path Does Not Follow the URI Specification	`user/path/url-rewriter`
429 Concurrent Connection Limit Reached	`user/rate-limit/http-endpoint-listener`
429 Rate Limit Is Exceeded	`user/rate-limit/rate-limiter`
400 REST to SOAP Conversion Failed	`user/rest-2-soap-gateway`
404 Invalid Path or Method	`user/routing`
400 SOAP to REST Transformation Failed	`user/soap-2-rest-gateway`
400 Error in STOMP Client	`user/stomp-client`
400 JSON Validation Failed	`user/validation/json-schema-validator`
400 OpenAPI Request Validation Failed	`user/validation/openapi/request`
500 OpenAPI Response Validation Failed	`user/validation/openapi/response`
400 XML Validation Failed	`user/validation/xml-schema-validator`
400 Not a SOAP Message	`user/ws-security`
400 and 405 Errors of wsdl2openapi	`user/wsdl2openapi`
415 and 400 Request Discarded by xmlProtection	`user/xml-protection`
400 XSLT Transformation Errors	`user/xslt-transformer`

Security Errors

A security plugin rejected the request, for example because of missing credentials, an invalid token or a CORS policy.

Error	Path
403 Access Denied	`security/access-control/authorization-denied`
401/403 API Key Rejected	`security/authorization-denied/api-key`
401 Basic Authentication Failed	`security/basic-authenticator`
403 CORS Credentials Not Allowed	`security/credentials-not-allowed/cors`
403 CORS Headers Not Allowed	`security/headers-not-allowed/cors`
401 JWT Rejected	`security/jwt-auth`
401 JWT Header Not JSON	`security/jwt-auth/jwt-header-not-json`
401 JWT Validation Failed	`security/jwt-auth/jwt-validation-failed`
401 Error Retrieving JWT	`security/jwt-auth/retrieving-jwt`
500 JWT Signing Failed	`security/jwt-sign/crypto`
500 Message Is Too Large	`security/limit-interceptor`
403 CORS Method Not Allowed	`security/method-not-allowed/cors`
500 OAuth2 Error from Authentication Server	`security/oauth2-callback-request-handler/oauth2-error-from-authentication-server`
403 CORS Origin Not Allowed	`security/origin-not-allowed/cors`
400/502 SQL Injection Blocked	`security/sql-injection-protection`
400 XML Security Policy Violated	`security/xml-protection`

Gateway Errors

Membrane could not reach the backend or received an invalid response from it.

Error	Path
502 Could Not Connect to Backend	`gateway/http-client/connect`
401 Protocol Upgrade Denied	`gateway/http-client/denied-protocol-upgrade`
502 Invalid Response Framing	`gateway/http-client/invalid-framing`
502 Unknown Backend Host	`gateway/http-client/unknown-host`
502 Could Not Obtain OAuth2 Token	`gateway/oauth2-client/oauth2-token`
502 Upstream Proxy Rejected CONNECT	`gateway/proxy/connect`

Internal Errors

A failure inside the gateway, in a plugin, a script or the processing of a message.

Error	Path
500 Error Dispatching Request in Admin Console	`internal/admin-rest`
500 Error Creating OpenAPI Publisher	`internal/api-docs/publisher-creation`
500 Error Generating OpenAPI Overview	`internal/api-docs/publisher-handling`
500 Could Not Create APIs JSON	`internal/apis-json`
500 OAuth2 Authorization Endpoint Error	`internal/auth-endpoint-processor`
503 No Backend Node Available	`internal/balancer/node-dispatching`
500 Could Not Get Session Id	`internal/balancer/sessionid-extraction`
500 Error Performing Callout	`internal/call`
500 Error Processing Call Response	`internal/call/internal-calling`
500 Choose Expression Evaluation Failed	`internal/choose/expression-evaluation`
500 Virus Scanner Error	`internal/clam-av`
500 OAuth2 Default Endpoint Failure	`internal/defaultendpointprocessor`
500 Could Not Get Forwarding Destination	`internal/dispatching-interceptor`
500 Error in Admin Console Request	`internal/dynamic-admin-page`
500 Could Not Create Echo	`internal/echo`
500 OAuth2 Consent or Flow Start Failed	`internal/empty-endpoint-processor`
500 Error Initiating OAuth2 Flow	`internal/flow-initiator`
500 For Expression Failed	`internal/for`
500 Could Not Parse Query Parameters	`internal/form-validation`
500 Error Serializing Map to JSON in groovy	`internal/groovy/json-processing-1`
500 Error Sending Request to Backend	`internal/http-client`
504 Connection to Backend Timed Out	`internal/http-client/connect-timeout`
502 Backend Closed the Connection	`internal/http-client/socket-closed`
502 Error Communicating with Target	`internal/http-client/socket-exception`
504 Backend Did Not Respond in Time	`internal/http-client/socket-timeout`
500 Error During Request Processing	`internal/http-handler/error-during-request-phase`
500 No Response Was Generated	`internal/http-handler/no-response-produced`
500 HTTP/2 Request Without Response	`internal/http2-exchange-handler`
500 If Condition Failed	`internal/if`
500 Internal Routing Failed	`internal/internal-routing/request`
500 Internal Route Response Failed	`internal/internal-routing/response`
500 JavaScript Script Error	`internal/javascript`
500 Error Serializing Map to JSON in javascript	`internal/javascript/json-processing-1`
500 Error Serializing JavaScript Object to JSON	`internal/javascript/json-processing-2`
500 Error Validating Message (JSON Schema)	`internal/json-schema-validator/generic`
500 Kubernetes Admission Webhook Error	`internal/kubernetes-validation`
500 OAuth2 Login Dialog Failed	`internal/login-dialog-endpoint-processor`
500 Could Not Handle Login Request	`internal/login`
500 NTLM Authentication Failed	`internal/ntlm-authentication`
500 Error Handling Request in oauth2Resource2	`internal/oauth2-resource/request`
500 Error Handling Response in oauth2Resource2	`internal/oauth2-resource/response`
500 Token Validation Endpoint Failed	`internal/oauth2-token-validator`
500 Error Handling OpenAPI Overview	`internal/openapi-publisher`
500 Could Not Parse OpenAPI (Request)	`internal/openapi/request/openapi-parsing`
500 OpenAPI Parsing Error in Response Validation	`internal/openapi/response/openapi-parsing`
500 Could Not Connect to Database	`internal/provides-caller-statistics-as-json`
500 Cannot Evaluate Rate Limit Key	`internal/rate-limit/rate-limiter`
500 Could Not Replace Body	`internal/regex-replacer`
500 Could Not Create Response	`internal/return`
500 Could Not Parse Target URL	`internal/reverse-proxy`
500 OAuth2 Token Revocation Failed	`internal/revocation-endpoint-processor`
500 Could Not Process SOAP Request	`internal/sample-soap-service`
500 Error Validating Message (Schematron)	`internal/schematron-validator/generic`
500 Groovy Script Error	`internal/scripting/groovy/script-execution`
500 Error Evaluating setBody Expression	`internal/setbody`
500 setHeader Expression Error	`internal/setheader`
500 setProperty Expression Error	`internal/setproperty`
500 Error Inspecting Message for SQL Injection	`internal/sql-injection-protection`
500 Template Expression Failed	`internal/template/execution`
500 Groovy Error in XML Template	`internal/template/groovy`
500 Template Rendering Failed	`internal/template/rendering`
500 OAuth2 Token Endpoint Error	`internal/tokenendpointprocessor`
500 OAuth2 Userinfo Endpoint Error	`internal/user-info-endpoint-processor`
500 Error Parsing JSON in json2Xml	`internal/validation/json/json-2-xml`
500 Could Not Resolve File	`internal/web-server`
500 Error Serving Document	`internal/web-server/request`
500 Could Not Create URI	`internal/web-server/uri-creation`
500 Error Dispatching Request in Web Service Explorer	`internal/web-service-explorer`
500 Could Not Apply WS-Security	`internal/ws-security`
500 Could Not Rewrite Endpoint	`internal/wsa-endpoint-rewriter`
500 Could Not Return WSDL Document	`internal/wsdl-publisher`
500 Error Rewriting URI in WSDL	`internal/wsdl-rewriting`
500 Error Validating Message (WSDL)	`internal/wsdl-validator/generic`
500 WSDL to OpenAPI Conversion Error	`internal/wsdl2openapi`
400 Could Not Transform XML to JSON	`internal/xml-2-json/request`
500 Could Not Transform XML to JSON	`internal/xml-2-json/response`
500 XML Error in xmlContentFilter	`internal/xml-content-filter`
500 Error Inspecting Body in xmlProtection	`internal/xml-protection`
500 Error Validating Message (XML Schema)	`internal/xml-schema-validator/generic`
500 XSLT Transformation Failed	`internal/xslt-transformer`

Operation Errors

The backend reported a failed operation, for example a SOAP fault.

Error	Path
500 Operation Failed in wsdl2openapi	`operation-error/wsdl2openapi`

Plugin-Specific Errors

Some errors can occur in any plugin. Their path ends in or contains the name of the plugin that raised the error. Plugins that have a page of their own for the same path are listed in the tables above.

Exception in a Plugin

A plugin threw an exception that it did not turn into an error response itself.

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Request Body Could Not Be Read

A plugin could not read the request body, because it was incomplete or broken.

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access-control acme-http-challenge admin-rest api-docs api-key apis-json balancer basic-authenticator call choose clam-av dispatching-interceptor dynamic-admin-page echo flow-initiator for form-validation groovy http-2-xml http-client if internal-routing javascript json-2-xml json-protection json-schema-validator jwt-sign kubernetes-validation limit-interceptor login ntlm-authentication oauth2-client oauth2-resource oauth2-token-validator openapi openapi-publisher provides-caller-statistics-as-json rate-limiter regex-replacer rest-2-soap-gateway return reverse-proxy sample-soap-service schematron-validator setbody setheader setproperty soap-2-rest-gateway sql-injection-protection stomp-client template url-rewriter web-server web-service-explorer ws-security wsa-endpoint-rewriter wsdl-publisher wsdl-rewriting wsdl-validator wsdl2openapi xml-2-json xml-content-filter xml-protection xml-schema-validator xslt-transformer

Request Body Could Not Be Decoded

A plugin could not decode a gzip, deflate or br request body.

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Message Body Could Not Be Read

A plugin could not read a message body, usually the response of the backend.

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Still stuck? See the troubleshooting guide or ask on GitHub Issues. For commercial support, contact info@predic8.de.