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I have a problem with Spring Boot configuration. I got exception on some mobile devices which should use sockets:

java.lang.IllegalArgumentException: Async support must be enabled on a servlet and for all filters involved in async request processing. This is done in Java code using the Servlet API or by adding "<async-supported>true</async-supported>" to servlet and filter declarations in web.xml. Also you must use a Servlet 3.0+ container
    at org.springframework.util.Assert.isTrue(Assert.java:65)
    at org.springframework.http.server.ServletServerHttpAsyncRequestControl.<init>(ServletServerHttpAsyncRequestControl.java:59)
    at org.springframework.http.server.ServletServerHttpRequest.getAsyncRequestControl(ServletServerHttpRequest.java:202)
    at org.springframework.web.socket.sockjs.transport.session.AbstractHttpSockJsSession.handleInitialRequest(AbstractHttpSockJsSession.java:202)
    at org.springframework.web.socket.sockjs.transport.handler.AbstractHttpSendingTransportHandler.handleRequestInternal(AbstractHttpSendingTransportHandler.java:66)
    at org.springframework.web.socket.sockjs.transport.handler.AbstractHttpSendingTransportHandler.handleRequest(AbstractHttpSendingTransportHandler.java:58)
    at org.springframework.web.socket.sockjs.transport.TransportHandlingSockJsService.handleTransportRequest(TransportHandlingSockJsService.java:254)
    at org.springframework.web.socket.sockjs.support.AbstractSockJsService.handleRequest(AbstractSockJsService.java:322)
    at org.springframework.web.socket.sockjs.support.SockJsHttpRequestHandler.handleRequest(SockJsHttpRequestHandler.java:88)
    at org.springframework.web.servlet.mvc.HttpRequestHandlerAdapter.handle(HttpRequestHandlerAdapter.java:51)
    at org.springframework.web.servlet.DispatcherServlet.doDispatch(DispatcherServlet.java:938)
    at org.springframework.web.servlet.DispatcherServlet.doService(DispatcherServlet.java:870)
    at org.springframework.web.servlet.FrameworkServlet.processRequest(FrameworkServlet.java:961)
    at org.springframework.web.servlet.FrameworkServlet.doPost(FrameworkServlet.java:863)
    at javax.servlet.http.HttpServlet.service(HttpServlet.java:646)
    at org.springframework.web.servlet.FrameworkServlet.service(FrameworkServlet.java:837)
    at javax.servlet.http.HttpServlet.service(HttpServlet.java:727)
As I see from the exception, I have to enable async processing by adding true into the web.xml file. But this is the problem because I don't have it - our project uses Spring Boot. 
Is there any way to provide the same functionality in Spring Boot like  does?
You just need to define dispatcherServlet @Bean:
@Bean
public ServletRegistrationBean<DispatcherServlet> dispatcherServlet() {
    DispatcherServletRegistrationBean registration = new DispatcherServletRegistrationBean(
            new DispatcherServlet(), "/");
    registration.setAsyncSupported(true);
    return registration;
It overrides that default one from DispatcherServletAutoConfiguration.
                If it complains about raw types, write ServletRegistrationBean<DispatcherServlet> instead of ServletRegistrationBean.
– Florian F
                Apr 9 at 21:01
                Or just DispatcherServletRegistrationBean. At the time I wrote this answer there was no that generic type on the ServletRegistrationBean.
– Artem Bilan
                Apr 10 at 13:13
Even though I am late to the party I am posting my working solution for posterity.
I had faced the same issue and tried the solution suggested by @Artem Bilan. But after debugging the code, I came to know that the servletRegistrationBean.isAsyncSupported() is by default true.
The actual error is being generated by the code block is from the method org.springframework.web.context.request.async.StandardServletAsyncWebRequest.startAsync()  and we are getting this error when getRequest().isAsyncSupported() is false. Despite the ServletRegistrationBean#asyncSupported value is true, HttpServletRequest#isAsyncSupported() method value is always set to false for all API requests.
The Exerpt of the code block Code Reference
Assert.state(getRequest().isAsyncSupported(),
                "Async support must be enabled on a servlet and for all filters involved " +
                "in async request processing. This is done in Java code using the Servlet API " +
                "or by adding \"<async-supported>true</async-supported>\" to servlet and " +
                "filter declarations in web.xml.");
When analyzing further, I came to know that requestAttributes -> Globals.ASYNC_SUPPORTED_ATTR decides whether the request has to be processed in an Async way or not. 
During the normal scenario, the requests do not have Globals.ASYNC_SUPPORTED_ATTR requestAttribute, hence request.asyncSupported will be false, if we manually add that requestAttribute ASYNC_SUPPORTED_ATTR value as true for all the requests using something like filters then request#asyncSupported value will be set to true as per the below code block Code Reference
specialAttributes.put(Globals.ASYNC_SUPPORTED_ATTR,
                new SpecialAttributeAdapter() {
                    @Override
                    public Object get(Request request, String name) {
                        return request.asyncSupported;
                    @Override
                    public void set(Request request, String name, Object value) {
                        Boolean oldValue = request.asyncSupported;
                        request.asyncSupported = (Boolean)value;
                        request.notifyAttributeAssigned(name, value, oldValue);
Though there is no explicit answer, I have implemented a workaround for this issue. To Summarize all the required changes are listed below:
Add a filter to set the request attribute as request.setAttribute(Globals.ASYNC_SUPPORTED_ATTR, true) 
@Component
public class AsyncSupportFilter extends OncePerRequestFilter {
    @Override
    protected void doFilterInternal(HttpServletRequest request, HttpServletResponse response, FilterChain chain) throws IOException, ServletException {
        request.setAttribute(Globals.ASYNC_SUPPORTED_ATTR, true);
        chain.doFilter(request, response);
@Component
@EnableWebSecurity
public class SecurityConfig extends WebSecurityConfigurerAdapter {
   @Autowired
   private AsyncSupportFilter asyncSupportFilter = null;
   @Override
   public void configure(HttpSecurity httpSecurity) {
       httpSecurity.addFilter(asyncSupportFilter);
       // we can add the filter before any filter like as httpSecurity.addFilterBefore(asyncSupportFilter , BasicAuthenticationFilter.class);
                I used this filter and it solved my problem. Note that, I didn't add the filter into the filter chain. Spring is handling that automatically.
– Halil
                Jul 24, 2020 at 19:31
Maybe it worth to mention that Spring Boot has async-support enabled by default for dispatcher servlet and all filters
Quotation from github:
  
We automatically set async-supported to true
  because the DispatcherServlet knows how to work with such requests and
  it's basically up to individual controller methods to return something
  like a DeferredResult. Furthermore, we also set async-supported for
  any filter (provided via getServletFilters) along with setting the
  DispatcherType for each filter to include ASYNC.
At least my practice supports this statement
                @Antoniossss that my answer was made during a migration project of a monolith spring (not spring boot) application to a set of standalone spring boot services. Previous, monolithic, non-spring boot version of the app had to turn on async-supported explicitly as far as I remember.
– AlexK
                Feb 6, 2020 at 3:55
                The behavior has changed in Spring Boot? The abovementioned statement was made by Spring Boot authors in 2014.....
– AlexK
                Feb 6, 2020 at 13:30
                I say it too but too but it was just not wrorking. We had to ass something like @EnableAsync somewhere - cannot remember exactly, but it was a matter of singe annotation (that does not relates to this at first glance)
– Antoniossss
                Feb 6, 2020 at 14:07
@WebFilter(value = {"/subscriberinfo/query/single/*"}, asyncSupported = true)
public class ...Filter{
        
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