OpenAPITools/openapi-generator · error · RuntimeException

Empty method/operation name (operationId) not allowed

Error message

Empty method/operation name (operationId) not allowed

What it means

Error "Empty method/operation name (operationId) not allowed" thrown in OpenAPITools/openapi-generator.

Source

Thrown at modules/openapi-generator/src/main/java/org/openapitools/codegen/languages/HaskellHttpClientCodegen.java:1262

    @Override
    public String toApiFilename(String name) {
        return toTypeName("Api", name);
    }

    @Override
    public String apiFileFolder() {
        return outputFolder + File.separator + this.modulePath + File.separator + "API";
    }

    public String toTypeName(String prefix, String name) {
        name = escapeIdentifier(prefix, camelize(sanitizeName(name)));
        return name;
    }

    @Override
    public String toOperationId(String operationId) {
        if (StringUtils.isEmpty(operationId)) {
            throw new RuntimeException("Empty method/operation name (operationId) not allowed");
        }
        operationId = escapeIdentifier("op", camelize(sanitizeName(operationId), LOWERCASE_FIRST_LETTER));
        return operationId;
    }

    public String escapeIdentifier(String prefix, String name) {
        if (StringUtils.isBlank(prefix)) return name;

        if (isReservedWord(name)) {
            name = prefix + name;
        }
        if (name.matches("^\\d.*")) {
            name = prefix + name; // e.g. 200Response => Model200Response (after camelize)
        }
        if (languageSpecificPrimitives.contains(name)) {
            name = prefix + name;
        }
        if (typeMapping.containsValue(name)) {

View on GitHub (pinned to fcec517be3)

Solutions

1. Provide a non-empty operationId for every operation in the OpenAPI spec.

When it happens

Trigger: Thrown when an operation in the OpenAPI spec has an empty or missing operationId while generating a Haskell http-client. Provide a non-empty operationId for every operation.

Common situations: See trigger scenarios.

AI-assisted analysis of OpenAPITools/openapi-generator@fcec517be3 (2026-08-22). Data as JSON: /api/errors/c428148c378edceb. Report an issue: GitHub.