Хммм. Ну скажу точно, переустановка УТМа не помогла. Ситуация такая же.
Надо было наверное сразу кидать, чёт я тупанул. Вот полностью что пишет в лог после запроса на проверку
2025-03-11 12:27:53,102 ERROR ru.centerinform.transport.backbone.http.controller.api.v2.a - Ошибка запроса на /websocket/884/g5i2wf40/xhr_streaming
org.springframework.http.converter.HttpMessageNotWritableException: No converter for [class java.util.LinkedHashMap] with preset Content-Type 'application/javascript;charset=UTF-8'
2025-03-11 12:27:53,102 WARN org.springframework.web.servlet.mvc.method.annotation.ExceptionHandlerExceptionResolver - Failure in @ExceptionHandler ru.centerinform.transport.backbone.http.controller.api.v2.a#a(Throwable, ServletWebRequest)
org.springframework.http.converter.HttpMessageNotWritableException: No converter for [class java.util.LinkedHashMap] with preset Content-Type 'application/javascript;charset=UTF-8'
2025-03-11 12:27:53,103 WARN org.springframework.web.servlet.mvc.support.DefaultHandlerExceptionResolver - Resolved [org.springframework.http.converter.HttpMessageNotWritableException: No converter for [class java.util.LinkedHashMap] with preset Content-Type 'application/javascript;charset=UTF-8']
2025-03-11 12:27:53,599 WARN org.springframework.web.socket.sockjs.transport.handler.DefaultSockJsService - Origin check enabled but transport 'jsonp' does not support it.
2025-03-11 12:27:53,941 ERROR ru.centerinform.transport.backbone.http.controller.api.v2.a - Ошибка запроса на /websocket/884/n2sbatzn/eventsource
org.springframework.http.converter.HttpMessageNotWritableException: No converter for [class java.util.LinkedHashMap] with preset Content-Type 'text/event-stream;charset=UTF-8'
2025-03-11 12:27:53,942 WARN org.springframework.web.servlet.mvc.method.annotation.ExceptionHandlerExceptionResolver - Failure in @ExceptionHandler ru.centerinform.transport.backbone.http.controller.api.v2.a#a(Throwable, ServletWebRequest)
org.springframework.http.converter.HttpMessageNotWritableException: No converter for [class java.util.LinkedHashMap] with preset Content-Type 'text/event-stream;charset=UTF-8'
2025-03-11 12:27:53,942 WARN org.springframework.web.servlet.mvc.support.DefaultHandlerExceptionResolver - Resolved [org.springframework.http.converter.HttpMessageNotWritableException: No converter for [class java.util.LinkedHashMap] with preset Content-Type 'text/event-stream;charset=UTF-8']
2025-03-11 12:27:55,740 ERROR org.apache.catalina.core.ContainerBase.[Tomcat].[localhost].[/].[dispatcherServlet] - Servlet.service() for servlet [dispatcherServlet] threw exception
java.lang.IllegalStateException: getOutputStream() has already been called for this response