Setting Undertow default server needs validation of provided server to avoid broken Wildfly configuration --------------------------------------------------------------------------------------------------------- Key: WFLY-10188 URL: https://issues.jboss.org/browse/WFLY-10188 Project: WildFly Issue Type: Bug Components: Web (Undertow) Affects Versions: 12.0.0.Final Reporter: Pavel Jelinek Assignee: Stuart Douglas Priority: Critical Undertow server needs default-host to be set to be able to be used as Undertow subsystem default-server otherwise Wildfly would not start due to: {code} ERROR [org.jboss.as.controller] (Controller Boot Thread) WFLYCTL0362: Capabilities required by resource '/subsystem=undertow' are not available: org.wildfly.undertow.host.test-server.default-host; Possible registration points for this capability: /subsystem=undertow/server=*/host=* {code} This is dangerous as after calling a {{reload}} operation, the server simply fails and crashes. One can accidentaly kill the server with this and \!manual\! fix is necessary to the configuration to be able to start server again. I think that there should be some check that configuration of the newly created server is complete and valid before it is set as a default server.