OpenAPITools/openapi-generator · error · RuntimeException

Invalid HTTP library {library}. Only restsharp, httpclient a

Error message

Invalid HTTP library {library}. Only restsharp, httpclient are supported.

What it means

Error "Invalid HTTP library {library}. Only restsharp, httpclient are supported." thrown in OpenAPITools/openapi-generator.

Source

Thrown at modules/openapi-generator/src/main/java/org/openapitools/codegen/languages/CSharpReducedClientCodegen.java:582

        if (isEmpty(apiPackage)) {
            setApiPackage("Api");
        }
        if (isEmpty(modelPackage)) {
            setModelPackage("Model");
        }

        clientPackage = "Client";

        if (RESTSHARP.equals(getLibrary())) {
            additionalProperties.put("useRestSharp", true);
            needsCustomHttpMethod = true;
        } else if (HTTPCLIENT.equals(getLibrary())) {
            setLibrary(HTTPCLIENT);
            additionalProperties.put("useHttpClient", true);
            needsUriBuilder = true;
        } else {
            throw new RuntimeException("Invalid HTTP library " + getLibrary() + ". Only restsharp, httpclient are supported.");
        }

        String inputFramework = (String) additionalProperties.getOrDefault(CodegenConstants.DOTNET_FRAMEWORK, defaultFramework.name);
        String[] frameworks;
        List<FrameworkStrategy> strategies = new ArrayList<>();

        if (inputFramework.contains(";")) {
            // multiple target framework
            frameworks = inputFramework.split(";");
            additionalProperties.put("multiTarget", true);
        } else {
            // just a single value
            frameworks = new String[]{inputFramework};
        }

        for (String framework : frameworks) {
            boolean strategyMatched = false;
            for (FrameworkStrategy frameworkStrategy : frameworkStrategies) {

View on GitHub (pinned to fcec517be3)

Solutions

1. Set the 'library' option to 'restsharp' or 'httpclient'.

When it happens

Trigger: Thrown when the 'library' option for the C# reduced client generator is not 'restsharp' or 'httpclient'. Set library to one of those two values.

Common situations: See trigger scenarios.

AI-assisted analysis of OpenAPITools/openapi-generator@fcec517be3 (2026-08-22). Data as JSON: /api/errors/bdfdd174c649c288. Report an issue: GitHub.