OpenAPITools/openapi-generator · error · ResponseStatusException

No OpenAPI specification was supplied

Error message

No OpenAPI specification was supplied

What it means

Thrown by the generate endpoints when a GeneratorInput was supplied but contains neither a usable spec nor an openAPIUrl (Generator.java:89-100). A spec that is exactly {} is explicitly normalized to null ('ignoring empty spec', Generator.java:82-85), so it counts as absent too. The service needs exactly one source of truth — inline spec or remote URL — and refuses to generate from options alone.

Source

Thrown at modules/openapi-generator-online/src/main/java/org/openapitools/codegen/online/service/Generator.java:99

        JsonNode node = opts.getSpec();
        if (node != null && "{}".equals(node.toString())) {
            LOGGER.debug("ignoring empty spec");
            node = null;
        }
        OpenAPI openapi;
        ParseOptions parseOptions = new ParseOptions();
        parseOptions.setResolve(true);
        if (node == null) {
            if (opts.getOpenAPIUrl() != null) {
                if (opts.getAuthorizationValue() != null) {
                    List<AuthorizationValue> authorizationValues = new ArrayList<>();
                    authorizationValues.add(opts.getAuthorizationValue());
                    openapi = new OpenAPIParser().readLocation(opts.getOpenAPIUrl(), authorizationValues, parseOptions).getOpenAPI();
                } else {
                    openapi = new OpenAPIParser().readLocation(opts.getOpenAPIUrl(), null, parseOptions).getOpenAPI();
                }
            } else {
                throw new ResponseStatusException(HttpStatus.BAD_REQUEST, "No OpenAPI specification was supplied");
            }
        } else if (opts.getAuthorizationValue() != null) {
            List<AuthorizationValue> authorizationValues = new ArrayList<>();
            authorizationValues.add(opts.getAuthorizationValue());
            openapi = new OpenAPIParser().readContents(node.toString(), authorizationValues, parseOptions).getOpenAPI();

        } else {
            openapi = new OpenAPIParser().readContents(node.toString(), null, parseOptions).getOpenAPI();
        }
        if (openapi == null) {
            throw new ResponseStatusException(HttpStatus.BAD_REQUEST, "The OpenAPI specification supplied was not valid");
        }


        // do not use opts.getOptions().get("outputFolder") as the input can contain ../../
        // to access other folders in the server
        String destPath = language + "-" + type.getTypeName();

View on GitHub (pinned to fcec517be3)

Solutions

1. Include exactly one of {"spec": {...}} or {"openAPIUrl": "https://..."} in the request body
2. Check field spelling: the model expects 'spec' and 'openAPIUrl' — verify with a serialized sample request
3. Don't send an empty {} spec; if you have no local spec, pass the URL where it is published

Example fix

// before
GeneratorInput in = new GeneratorInput();
in.setOptions(Map.of("packageName", "com.acme"));   // no spec, no url -> 400

// after
GeneratorInput in = new GeneratorInput();
in.setOpenAPIUrl("https://petstore3.swagger.io/api/v3/openapi.json");
in.setOptions(Map.of("packageName", "com.acme"));

// require exactly one spec source before sending
boolean hasSpec = input.getSpec() != null && !"{}".equals(input.getSpec().toString());
boolean hasUrl = input.getOpenAPIUrl() != null;
if (!hasSpec && !hasUrl) throw new IllegalArgumentException("supply spec or openAPIUrl");

boolean hasSpecSource(GeneratorInput in) {
    if (in == null) return false;
    JsonNode s = in.getSpec();
    return (s != null && !s.isNull() && !s.isEmpty()) || in.getOpenAPIUrl() != null;
}

When it happens

Trigger: Body {"options":{...}} with no spec/openAPIUrl keys; body {} sent just to satisfy 285; spec sent as the literal string "{}" or an empty JSON object; openAPIUrl key misspelled (e.g. openApiUrl, openapiUrl) so Jackson drops it.

Common situations: Clients that build the request from optional config maps where both fields ended up unset; serialization bugs (wrong field name casing) silently dropping the URL; UIs with two inputs where the user filled neither.

Related errors

• The OpenAPI specification supplied was not valid
• Framework is required
• No options were supplied
• Unsupported target " + language + " supplied
• In rule: " + rule + "the operands were not provided in the f

AI-assisted analysis of OpenAPITools/openapi-generator@fcec517be3 (2026-08-22). Data as JSON: /api/errors/23aef1a4a2058828. Report an issue: GitHub.