Yeah, I encounter this exception while I was using code. I agree that the NoNodeException here is harmless here. Here is the stack trace:

````
00:10:04,015 ERROR main-EventThread imps.CuratorFrameworkImpl:512 - Watcher exception
org.springframework.xd.dirt.zookeeper.ZooKeeperAccessException: KeeperErrorCode = NoNode for /xd/taps/stream:s1.http.0
	at org.springframework.xd.dirt.zookeeper.ZooKeeperUtils.wrapThrowable(ZooKeeperUtils.java:53)
	at org.springframework.xd.dirt.zookeeper.ZooKeeperUtils.wrapThrowable(ZooKeeperUtils.java:37)
	at org.springframework.xd.dirt.server.ContainerRegistrar.unregisterTap(ContainerRegistrar.java:314)
	at org.springframework.xd.dirt.server.ContainerRegistrar.undeployModule(ContainerRegistrar.java:263)
	at org.springframework.xd.dirt.server.ContainerRegistrar$StreamModuleWatcher.process(ContainerRegistrar.java:696)
	at org.apache.curator.framework.imps.NamespaceWatcher.process(NamespaceWatcher.java:56)
	at org.apache.zookeeper.ClientCnxn$EventThread.processEvent(ClientCnxn.java:522)
	at org.apache.zookeeper.ClientCnxn$EventThread.run(ClientCnxn.java:498)
Caused by: org.apache.zookeeper.KeeperException$NoNodeException: KeeperErrorCode = NoNode for /xd/taps/stream:s1.http.0
	at org.apache.zookeeper.KeeperException.create(KeeperException.java:111)
	at org.apache.zookeeper.KeeperException.create(KeeperException.java:51)
	at org.apache.zookeeper.ZooKeeper.delete(ZooKeeper.java:873)
	at org.apache.curator.framework.imps.DeleteBuilderImpl$5.call(DeleteBuilderImpl.java:239)
	at org.apache.curator.framework.imps.DeleteBuilderImpl$5.call(DeleteBuilderImpl.java:234)
	at org.apache.curator.RetryLoop.callWithRetry(RetryLoop.java:107)
	at org.apache.curator.framework.imps.DeleteBuilderImpl.pathInForeground(DeleteBuilderImpl.java:230)
	at org.apache.curator.framework.imps.DeleteBuilderImpl.forPath(DeleteBuilderImpl.java:215)
	at org.apache.curator.framework.imps.DeleteBuilderImpl.forPath(DeleteBuilderImpl.java:42)
	at org.springframework.xd.dirt.server.ContainerRegistrar.unregisterTap(ContainerRegistrar.java:307)
	... 5 more

````