used inside Wildfly 21.0.2.Final outline structure:   EAR: application.xml: module/web/ <context-root>/manager</context-root> WAR: web.xml: this exists (nothing notable configured inside) jboss-web.xml: <context-root>/manager</context-root> <virtual-host>default-host</virtual-host> Servlet registered at WAR deployment startup with: ServletRegistration.Dynamic#addMappings(String[] { "/", "/*", "" }) Access to servlet invoked from browser results: Successful usage: http://localhost:8080/manager/index.html (HTTP/200 that is expected) http://localhost:8080/manager/ (HTTP/200 that is expected) The bug being reported here: http://localhost:8080/manager (NPE from HttpServletRequestImpl.getHttpServletMapping(HttpServletRequestImpl.java:253)) NOTE the lack of trailing slash in the path The servlet code calls: HttpServletRequest#getHttpServletMapping() I hope this is enough information to assist.     https://github.com/undertow-io/undertow/blob/2.2.2.Final/servlet/src/main/java/io/undertow/servlet/handlers/ServletPathMatch.java There is plenty of code here that will set this.remaining=null or take any value from caller