What causes "http client not set" in karatelabs/karate?

Create and set a client: new HttpRequestBuilder(new DefaultHttpClientFactory().create())

karatelabs/karate · error · RuntimeException

http client not set

Error message

http client not set

What it means

HttpRequestBuilder.invoke() sends the built HttpRequest through the configured HttpClient. The builder was created without a client (never passed via the constructor or a setter), so there is nothing to execute the request with, and the builder throws before doing any I/O.

Solutions

Create and set a client: new HttpRequestBuilder(new DefaultHttpClientFactory().create())
Prefer high-level entry points such as karate.http(...) / HttpRequest helpers that wire a client for you
If you only need a curl representation, call toCurlCommand() instead of invoke()
Audit custom integration code for builders constructed without a client parameter

Example fix

// before
HttpRequestBuilder builder = new HttpRequestBuilder();
builder.url("http://example.com").invoke(); // throws
// after
HttpRequestBuilder builder = new HttpRequestBuilder(new DefaultHttpClientFactory().create());
builder.url("http://example.com").invoke();

Defensive patterns

Strategy: try-catch

Validate before calling

if (client == null) throw new IllegalStateException('set an HttpClient on the builder before invoke()');

Try / catch

try {
  builder.invoke();
} catch (RuntimeException e) {
  if (e.getMessage().equals("http client not set")) {
    builder = new HttpRequestBuilder(new DefaultHttpClientFactory().create()).url(builderUrl);
    // retry the invoke
  } else { throw e; }
}

Prevention

Construct builders with a client: new HttpRequestBuilder(httpClient)
Prefer karate.http(...) or library helpers that wire a client automatically
Use toCurlCommand() for inspection-only flows instead of invoking a client-less builder

When it happens

Trigger: Calling invoke()/response()/method()/request()/proceed()/exception() on an HttpRequestBuilder constructed with new HttpRequestBuilder() and no client set; obtaining a builder through a code path that bypasses the HttpClientFactory; holding a builder beyond a scope where its client was reset.

Common situations: Embedding Karate's HTTP DSL in custom Java code and forgetting to create a client via new DefaultHttpClientFactory().create(); framework integrations that build requests for serialization (curl export) but then attempt to execute them; configuration errors where the client bean was never injected.

Understand the failure class

Background: "This is a bug, please report it": internal invariant violations, unreachable panics, and SNH errors explained — this error's family across 47 libraries.

Related errors

AI-assisted analysis of karatelabs/karate@a22eb90246 (2026-09-12). Data as JSON: /api/errors/4728975919fdd1c3. Report an issue: GitHub.

Appendix: source

Thrown at karate-core/src/main/java/io/karatelabs/http/HttpRequestBuilder.java:143

        request.setUrl(getUri());
        if (multiPart != null) {
            request.setBodyDisplay(multiPart.getBodyForDisplay());
        }
        if (body != null) {
            request.setBody(Json.toBytes(body));
        }
        request.setHeaders(headers);
        // Also set params on request so InMemoryHttpClient and others can access them
        if (params != null) {
            request.setParams(params);
        }
        return request;
    }

    public HttpResponse invoke() {
        HttpRequest request = build();
        if (client == null) {
            throw new RuntimeException("http client not set");
        }
        reset();
        HttpResponse response = client.invoke(request);
        response.setRequest(request);
        // conversion-side stamp for ANY client, on every lane that reaches this builder —
        // the step executor re-stamps the gherkin lanes, but karate.http() has only this
        if (configSupplier != null) {
            io.karatelabs.core.KarateConfig config = configSupplier.get();
            if (config != null) {
                response.setStrictParsing(config.isStrictResponseParsing());
            }
        }
        return response;
    }

    public HttpResponse invoke(String method) {
        this.method = method;
        return invoke();

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