OpenAPITools/openapi-generator · error · IllegalArgumentException

Invalid model property naming '{naming}'. Must be 'original'

Error message

Invalid model property naming '{naming}'. Must be 'original', 'camelCase', 'PascalCase' or 'snake_case'

What it means

Error "Invalid model property naming '{naming}'. Must be 'original', 'camelCase', 'PascalCase' or 'snake_case'" thrown in OpenAPITools/openapi-generator.

Source

Thrown at modules/openapi-generator/src/main/java/org/openapitools/codegen/languages/CSharpClientCodegen.java:619

                return 1;
        }
    };

    @Override
    public String getHelp() {
        return "Generates a C# client library (.NET Standard, .NET Core).";
    }

    public String getModelPropertyNaming() {
        return this.modelPropertyNaming;
    }

    public void setModelPropertyNaming(String naming) {
        if ("original".equals(naming) || "camelCase".equals(naming) ||
                "PascalCase".equals(naming) || "snake_case".equals(naming)) {
            this.modelPropertyNaming = naming;
        } else {
            throw new IllegalArgumentException("Invalid model property naming '" +
                    naming + "'. Must be 'original', 'camelCase', " +
                    "'PascalCase' or 'snake_case'");
        }
    }

    @Override
    public String getName() {
        return "csharp";
    }

    public String getNameUsingModelPropertyNaming(String name) {
        switch (CodegenConstants.MODEL_PROPERTY_NAMING_TYPE.valueOf(getModelPropertyNaming())) {
            case original:
                return name;
            case camelCase:
                return camelize(name, LOWERCASE_FIRST_LETTER);
            case PascalCase:
                return camelize(name);

View on GitHub (pinned to fcec517be3)

Solutions

1. Set modelPropertyNaming to one of 'original', 'camelCase', 'PascalCase' or 'snake_case'.

When it happens

Trigger: Thrown when the 'modelPropertyNaming' option for the C# client generator is not 'original', 'camelCase', 'PascalCase' or 'snake_case'.

Common situations: See trigger scenarios.

AI-assisted analysis of OpenAPITools/openapi-generator@fcec517be3 (2026-08-22). Data as JSON: /api/errors/3418c156194155aa. Report an issue: GitHub.