Hi everyone, This question is about a Spring Boot application running on an embedded Undertow. Once the application is deployed, serving some resources may randomly block. The requests to grab them stay pending. When refreshing the page, it may work or block on another resource. Besides this: refresh (f5) and force refresh (ctrl+f5) have the same outcome. Issue arise in multiple web browsers (Chrome, Edge, FF). No errors are logged back or front-end side. Since resources are sometimes served properly we can say that static resource auto discovery by the Spring Boot container works and that resources are not blocked by security filters. Switching to an embedded Tomcat fixes the issue. Could anyone help me figure why Undertow would behave like this ?