TL;DR The F5 BigPipe LTM uses HTTP/0.9 to send its HTTP monitoring requests by default. Wildfly 9.0 does not like this; moving to a monitor request of HTTP/1.1 fixed the problem. Caution: LTM 10.2.x and 11.x do not append a CR/LF to the end unless you are using Basic Authentication. This is contrary to previous …