Cannot resolve method 'doOnSuccessOrError' in 'Mono'

I have this Spring Gateway code which I want to migrate to latest Spring Cloud 3:

@Component
public class CorrelationIdApiFilter implements WebFilter {
  
  @Override
  public Mono<Void> filter(ServerWebExchange exchange, WebFilterChain chain) {
    if (......) {
      ServerWebExchange obj = ......

      return chain.filter(obj).doOnSuccessOrError((resp, ex) -> MDC.clear());
    }
    return chain.filter(exchange);
  }
}

I get error: Cannot resolve method 'doOnSuccessOrError' in 'Mono'

I tried to edit the code this way:

@Component
public class CorrelationIdApiFilter implements WebFilter {
  
  @Override
  public Mono<Void> filter(ServerWebExchange exchange, WebFilterChain chain) {
    if (......) {
      ServerWebExchange obj = ......

      return chain.filter(obj).doOnSuccess((resp) -> MDC.clear()).doOnError(ex);
    }
    return chain.filter(exchange);
  }
}

But I get Cannot resolve symbol 'ex'. Do you know what should be the proper way to migrate the code?

doOnSuccessOrError is deprecated and removed in 3.4.0. According to documentation

prefer using doOnNext(Consumer), doOnError(Consumer), doOnTerminate(Runnable) or doOnSuccess(Consumer)

In your case

return chain.filter(obj)
    .doOnSuccess(resp -> MDC.clear())
    .doOnError(ex -> MDC.clear());