OpenAPITools/openapi-generator · error · RuntimeException

Empty method name (operationId) not allowed

Error message

Empty method name (operationId) not allowed

What it means

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

Source

Thrown at modules/openapi-generator/src/main/java/org/openapitools/codegen/languages/ElixirClientCodegen.java:556

            name = "model_" + name; // e.g. return => ModelReturn (after camelize)
        }

        // model name starts with number
        if (name.matches("^\\d.*")) {
            LOGGER.warn("{} (model name starts with number) cannot be used as model name. Renamed to {}", name,
                    "model_" + name);
            name = "model_" + name; // e.g. 200Response => Model200Response (after camelize)
        }

        return underscore(name);
    }

    @Override
    public String toOperationId(String operationId) {
        // throw exception if method name is empty (should not occur as an
        // auto-generated method name will be used)
        if (StringUtils.isEmpty(operationId)) {
            throw new RuntimeException("Empty method name (operationId) not allowed");
        }

        // method name cannot use reserved keyword, e.g. return
        if (isReservedWord(operationId)) {
            LOGGER.warn("{} (reserved word) cannot be used as method name. Renamed to {}", operationId,
                    underscore(sanitizeName("call_" + operationId)));
            return underscore(sanitizeName("call_" + operationId));
        }

        // operationId starts with a number
        if (operationId.matches("^\\d.*")) {
            LOGGER.warn("{} (starting with a number) cannot be used as method name. Renamed to {}", operationId,
                    underscore(sanitizeName("call_" + operationId)));
            operationId = "call_" + operationId;
        }

        return underscore(sanitizeName(operationId));
    }

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 an Elixir 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/bbbb15bea559ec6c. Report an issue: GitHub.