如果要检索错误详细信息：

WebClient webClient = WebClient.builder()
    .filter(ExchangeFilterFunction.ofResponseProcessor(clientResponse -> {
        if (clientResponse.statusCode().isError()) {
            return clientResponse.bodyToMono(ErrorDetails.class)
                    .flatMap(errorDetails -> Mono.error(new CustomClientException(clientResponse.statusCode(), errorDetails)));
        }
        return Mono.just(clientResponse);
    }))
    .build();

与

class CustomClientException extends WebClientException {
    private final HttpStatus status;
    private final ErrorDetails details;

    CustomClientException(HttpStatus status, ErrorDetails details) {
        super(status.getReasonPhrase());
        this.status = status;
        this.details = details;
    }

    public HttpStatus getStatus() {
        return status;
    }

    public ErrorDetails getDetails() {
        return details;
    }
}

并且ErrorDetails类Map错误体
按请求变量：

webClient.get()
    .exchange()
    .map(clientResponse -> {
        if (clientResponse.statusCode().isError()) {
            return clientResponse.bodyToMono(ErrorDetails.class)
                    .flatMap(errorDetails -> Mono.error(new CustomClientException(clientResponse.statusCode(), errorDetails)));
        }
        return clientResponse;
    })

正如@Frischling建议的那样，我将请求更改为如下所示

return webClient.getWebClient()
 .post()
 .uri("/api/Card")
 .body(BodyInserters.fromObject(cardObject))
 .exchange()
 .flatMap(clientResponse -> {
     if (clientResponse.statusCode().is5xxServerError()) {
        clientResponse.body((clientHttpResponse, context) -> {
           return clientHttpResponse.getBody();
        });
     return clientResponse.bodyToMono(String.class);
   }
   else
     return clientResponse.bodyToMono(String.class);
});

我还注意到有几个状态代码，从1xx到5xx，这将使我在不同情况下的错误处理更容易

看一下.onErrorMap()，它为您提供了要查看的异常。由于您可能还需要查看exchange（）的body（），因此不要使用retrieve，而是

.exchange().flatMap((ClientResponse) response -> ....);

我也在纠结这个问题
执行此操作以获取字符串形式的body

.retrieve()
.onStatus(HttpStatus::isError, clientResponse -> {
               clientResponse.bodyToMono(String.class).blockOptional().ifPresent(log::info);
                return Mono.error(RuntimeException::new);})

这是我找到的解决办法。