diff --git a/src/main/java/net/onrc/onos/registry/controller/ControllerRegistryResource.java b/src/main/java/net/onrc/onos/registry/controller/ControllerRegistryResource.java
index 51f1d32..5da2e7c 100644
--- a/src/main/java/net/onrc/onos/registry/controller/ControllerRegistryResource.java
+++ b/src/main/java/net/onrc/onos/registry/controller/ControllerRegistryResource.java
@@ -3,6 +3,10 @@
 import java.util.ArrayList;
 import java.util.Collection;
 
+import org.restlet.Response;
+import org.restlet.data.Status;
+import org.restlet.representation.Representation;
+import org.restlet.representation.StringRepresentation;
 import org.restlet.resource.Get;
 import org.restlet.resource.ServerResource;
 import org.slf4j.Logger;
@@ -27,8 +31,13 @@
 		
 		if (controllers == null){
 			controllers = new ArrayList<String>();
+			Response response = getResponse();
+			response.setStatus(Status.CLIENT_ERROR_NOT_FOUND);
+			Representation error = new StringRepresentation("Null data returned. Zookeeper connection may be down");
+			response.setEntity(error);
+			return null;
 		}
-		
+
 		return controllers;
 	}
 	
diff --git a/src/main/java/net/onrc/onos/registry/controller/ZookeeperRegistry.java b/src/main/java/net/onrc/onos/registry/controller/ZookeeperRegistry.java
index fe758cd..7d1420a 100644
--- a/src/main/java/net/onrc/onos/registry/controller/ZookeeperRegistry.java
+++ b/src/main/java/net/onrc/onos/registry/controller/ZookeeperRegistry.java
@@ -236,7 +236,16 @@
 	public Collection<String> getAllControllers() throws RegistryException {
 		log.debug("Getting all controllers");
 		
+		//Rebuild the cache to make sure we have the latest data
+		//If we don't have ZK connection this will hang until we do. Undesirable.
+		try {
+			controllerCache.rebuild();
+		} catch (Exception e1) {
+			return null;
+		}
+		
 		List<String> controllers = new ArrayList<String>();
+		
 		for (ChildData data : controllerCache.getCurrentData()){
 
 			String d = null;
@@ -253,6 +262,7 @@
 
 	@Override
 	public void registerController(String id) throws RegistryException {
+		//TODO this isn't replaced if we lose Zookeeper connection
 		if (controllerId != null) {
 			throw new RegistryException(
 					"Controller already registered with id " + controllerId);