What are the scenarios when a WebClientRequestException is thrown?

Is there any comprehensive list of scenarios when a WebClientRequestException is thrown ?

As part of a Springboot project, there are several WebClientRequest exceptions I'm encountering like SSLException, ProxyConnectException, etc. To implement the retryLogic for the same, I need a comprehensive list, if available for which scenarios throw this Exception to ensure retry logic is needed for all of them.

A WebClientRequestException is thrown in a variety of scenarios when using Spring WebFlux's WebClient to perform HTTP requests. This exception is typically thrown during the execution of a request and when it is unsuccessfully and this exceptions that contain actual HTTP request data. It is a general-purpose exception related to problems that occur when trying to make an HTTP request with WebClient. Below are some common scenarios where a WebClientRequestException might be thrown:

• Connection Issues

  • Server Unreachable: When the client is unable to establish a connection to the server. This could happen due to network issues, incorrect URL, or server being down.
  • Timeouts: If the client cannot establish a connection within the specified timeout period, a timeout exception can occur. This can be either a connection timeout (when connecting to the server) or a read timeout (when waiting for the response).

• Invalid URL or URI

  • If the URL passed to the WebClient is malformed or invalid, such as a missing scheme (e.g., http:// or https://), it will result in a WebClientRequestException.

• Request Execution Failures

  • If there is an issue during the process of writing the request (such as serialization failures or invalid headers), WebClientRequestException can be thrown.
  • For example, if the body of a POST or PUT request cannot be serialized, or if there’s an issue with content-type or header configuration, the exception can occur.

This exception will be thrown on any unsuccessful request due to any general error cause. By comparing the Exception from getCause() method you can identify the root cause

    webClient.get()
             .uri("http://invalid-url") // This will cause a URISyntaxException
             .retrieve()
             .bodyToMono(String.class)
             .doOnError(e -> {
                 if (e instanceof WebClientRequestException) {
                     WebClientRequestException webClientException = (WebClientRequestException) e;
                     Throwable cause = webClientException.getCause();
                     
                     if (cause instanceof URISyntaxException) {
                         System.err.println("Invalid URI: " + cause.getMessage());
                     } else if (cause instanceof ConnectException) {
                         System.err.println("Connection error: " + cause.getMessage());
                     } else if (cause instanceof UnknownHostException) {
                         System.err.println("DNS resolution error: " + cause.getMessage());
                     } else {
                         System.err.println("Other error: " + cause.getClass().getName());
                     }
                 }
             })