To reproduce:

• comment (in stacks.xml) FLUSH in the "udp" section
• Run (e.g.) DrawMultiplexer

2282 [ERROR] JChannelFactory.connect(): - failed sending SERVICE_UP message
java.lang.IllegalStateException: Flush is not supported, add pbcast.FLUSH protocol to your configuration
at org.jgroups.JChannel.startFlush(JChannel.java:1765)
at org.jgroups.JChannel.startFlush(JChannel.java:1823)
at org.jgroups.JChannelFactory.connect(JChannelFactory.java:366)
at org.jgroups.mux.MuxChannel.connect(MuxChannel.java:126)
at org.jgroups.demos.DrawMultiplexer.start(DrawMultiplexer.java:40)
at org.jgroups.demos.DrawMultiplexer.main(DrawMultiplexer.java:29)
Exception in thread "main" java.lang.IllegalStateException: Flush is not supported, add pbcast.FLUSH protocol to your configuration
at org.jgroups.JChannel.stopFlush(JChannel.java:1828)
at org.jgroups.JChannelFactory.connect(JChannelFactory.java:377)
at org.jgroups.mux.MuxChannel.connect(MuxChannel.java:126)
at org.jgroups.demos.DrawMultiplexer.start(DrawMultiplexer.java:40)
at org.jgroups.demos.DrawMultiplexer.main(DrawMultiplexer.java:29)
Disconnected from the target VM, address: '127.0.0.1:2841', transport: 'socket'

Process finished with exit code 1