quarkusio/quarkus · error · WebApplicationException

Missing required param in method '<method>'

Error message

Missing required param in method '<method>'

What it means

SpringWebRequestParamHandler is a RESTEasy Reactive request filter installed when Spring-style required request parameter enforcement is active. In RESOLVE_METHOD_PARAMETERS phase it checks the query parameter map; if it is empty while the resource method declares required params, it throws a 400 Bad Request WebApplicationException naming the resource method.

Source

Thrown at extensions/spring-web/resteasy-reactive/runtime/src/main/java/io/quarkus/spring/web/resteasy/reactive/runtime/SpringRequestParamHandler.java:32

import org.jboss.resteasy.reactive.server.spi.ServerRestHandler;

/**
 * In Spring, parameters annotated with {@code @RequestParam} are required by default unless explicitly marked as
 * optional.
 * This {@link SpringRequestParamHandler} enforces the required constraint responding with a BAD_REQUEST status.
 *
 */
public class SpringRequestParamHandler implements HandlerChainCustomizer {
    @Override
    public List<ServerRestHandler> handlers(HandlerChainCustomizer.Phase phase, ResourceClass resourceClass,
            ServerResourceMethod resourceMethod) {
        if (phase == Phase.RESOLVE_METHOD_PARAMETERS) {
            return Collections.singletonList(new ServerRestHandler() {
                @Override
                public void handle(ResteasyReactiveRequestContext requestContext) throws Exception {
                    Map<String, List<String>> parametersMap = requestContext.serverRequest().getQueryParamsMap();
                    if (parametersMap.isEmpty()) {
                        throw new WebApplicationException("Missing required param in method '" + resourceMethod.getName() + "'",
                                Response.Status.BAD_REQUEST);
                    }
                }
            });
        }
        return Collections.emptyList();
    }

}

View on GitHub (pinned to e1c734241f)

Solutions

1. Send the required query parameters, e.g. GET /endpoint?name=value.
2. Mark the Spring @RequestParam as required = false and supply a defaultValue if the param is genuinely optional.
3. Fix the client code or proxy/gateway that strips the query string.

Example fix

// before (client)
GET /search

// after
GET /search?q=quarkus

// or relax the param: before @RequestParam String q
// after @RequestParam(required = false, defaultValue = "") String q

// client-side pre-check before calling the endpoint
if (!url.includes('?') || new URLSearchParams(url.split('?')[1]).size === 0) {
  throw new Error('required query params missing for ' + endpoint);
}

try {
  Response r = client.send(req);
} catch (WebApplicationException e) {
  if (e.getResponse().getStatus() == 400) {
    // fix request: append required query parameters
  } else throw e;
}

When it happens

Trigger: Calling a resource method that declares required @RequestParam entries (via the Spring param handler) without sending any query parameters on the request.

Common situations: Clients omitting query strings (e.g. a bookmarked URL without params); API consumers hitting the endpoint directly; missing client-side query building.

Understand the failure class

Background: "missing required argument" and "the following required arguments were not provided": what required-argument errors mean and how to fix them — this error's family across 20 libraries.

Related errors

• Usage of multiple methods using '@RequestMapping' is not all
• Unsupported HTTP method '<method>' for @RequestMapping. Offe
• Parameter: ${i} of the constructor of class '${resourceDotNa
• Parameter: ${i} of the constructor of class '${resourceDotNa
• Unsupported type '${jaxRSAnnotationOfParam.name()}' used as

AI-assisted analysis of quarkusio/quarkus@e1c734241f (2026-09-05). Data as JSON: /api/errors/9dae2ad67f0ebff9. Report an issue: GitHub.