diff --git a/api/src/com/cloud/exception/DiscoveredWithErrorException.java b/api/src/com/cloud/exception/DiscoveredWithErrorException.java
new file mode 100644
index 00000000000..6af3d386d3a
--- /dev/null
+++ b/api/src/com/cloud/exception/DiscoveredWithErrorException.java
@@ -0,0 +1,16 @@
+package com.cloud.exception;
+
+import com.cloud.utils.SerialVersionUID;
+
+public class DiscoveredWithErrorException extends DiscoveryException {
+    
+    private static final long serialVersionUID = SerialVersionUID.DiscoveredWithErrorException;
+
+    public DiscoveredWithErrorException(String msg) {
+        this(msg, null);
+    }
+    
+    public DiscoveredWithErrorException(String msg, Throwable cause) {
+        super(msg, cause);
+    }
+}
diff --git a/core/src/com/cloud/hypervisor/xen/resource/XenServerConnectionPool.java b/core/src/com/cloud/hypervisor/xen/resource/XenServerConnectionPool.java
index f9cef812e14..6e8097824e7 100644
--- a/core/src/com/cloud/hypervisor/xen/resource/XenServerConnectionPool.java
+++ b/core/src/com/cloud/hypervisor/xen/resource/XenServerConnectionPool.java
@@ -298,7 +298,7 @@ public class XenServerConnectionPool {
     }
     
   
-    public String getMasterIp(String ip, String username, String password) {
+    public String getMasterIp(String ip, String username, String password) throws XenAPIException {
         Connection slaveConn = null;
         try{ 
             slaveConn = new Connection(getURL(ip), 10);
@@ -312,6 +312,9 @@ public class XenServerConnectionPool {
             Host master = pr.master;
             masterIp = master.getAddress(slaveConn);
             return masterIp;
+        }catch(Types.SessionAuthenticationFailed e){
+        	s_logger.debug("Failed to slave local login to " + ip + " due to " + e.toString());
+        	throw e;
         }catch ( Exception e){
             s_logger.debug("Failed to slave local login to " + ip + " due to " + e.toString());
         } finally {
diff --git a/server/src/com/cloud/agent/manager/AgentManagerImpl.java b/server/src/com/cloud/agent/manager/AgentManagerImpl.java
index b26289c6ebf..ebf434b9288 100755
--- a/server/src/com/cloud/agent/manager/AgentManagerImpl.java
+++ b/server/src/com/cloud/agent/manager/AgentManagerImpl.java
@@ -106,6 +106,7 @@ import com.cloud.deploy.DeploymentPlanner.ExcludeList;
 import com.cloud.event.dao.EventDao;
 import com.cloud.exception.AgentUnavailableException;
 import com.cloud.exception.ConnectionException;
+import com.cloud.exception.DiscoveredWithErrorException;
 import com.cloud.exception.DiscoveryException;
 import com.cloud.exception.InsufficientServerCapacityException;
 import com.cloud.exception.InvalidParameterValueException;
@@ -970,7 +971,9 @@ public class AgentManagerImpl implements AgentManager, HandlerFactory, ResourceS
 			try {
 				resources = discoverer.find(dcId, podId, clusterId, uri,
 						username, password);
-			} catch (Exception e) {
+			} catch (DiscoveredWithErrorException e){ 
+				throw e;
+			}catch (Exception e) {
 				s_logger.info("Exception in host discovery process with discoverer: "
 						+ discoverer.getName()
 						+ ", skip to another discoverer if there is any");
diff --git a/server/src/com/cloud/hypervisor/kvm/discoverer/KvmServerDiscoverer.java b/server/src/com/cloud/hypervisor/kvm/discoverer/KvmServerDiscoverer.java
index bc039041f92..540a70e049e 100644
--- a/server/src/com/cloud/hypervisor/kvm/discoverer/KvmServerDiscoverer.java
+++ b/server/src/com/cloud/hypervisor/kvm/discoverer/KvmServerDiscoverer.java
@@ -40,6 +40,7 @@ import com.cloud.configuration.Config;
 import com.cloud.configuration.dao.ConfigurationDao;
 import com.cloud.dc.ClusterVO;
 import com.cloud.dc.dao.ClusterDao;
+import com.cloud.exception.DiscoveredWithErrorException;
 import com.cloud.exception.DiscoveryException;
 import com.cloud.host.Host;
 import com.cloud.host.HostVO;
@@ -157,7 +158,7 @@ public class KvmServerDiscoverer extends DiscovererBase implements Discoverer,
 			sshConnection.connect(null, 60000, 60000);
 			if (!sshConnection.authenticateWithPassword(username, password)) {
 				s_logger.debug("Failed to authenticate");
-				return null;
+				throw new DiscoveredWithErrorException("Authetication error");
 			}
 			
 			if (!SSHCmdHelper.sshExecuteCmd(sshConnection, "lsmod|grep kvm >& /dev/null", 3)) {
@@ -198,7 +199,9 @@ public class KvmServerDiscoverer extends DiscovererBase implements Discoverer,
 			
 			details.put("guid", guidWithTail);
 			return resources;
-		} catch (Exception e) {
+		} catch (DiscoveredWithErrorException e){ 
+			throw e;
+		}catch (Exception e) {
 			String msg = " can't setup agent, due to " + e.toString() + " - " + e.getMessage();
 			s_logger.warn(msg);
 		} finally {
diff --git a/server/src/com/cloud/hypervisor/xen/discoverer/XcpServerDiscoverer.java b/server/src/com/cloud/hypervisor/xen/discoverer/XcpServerDiscoverer.java
index 2da7594de01..3df1d63a095 100644
--- a/server/src/com/cloud/hypervisor/xen/discoverer/XcpServerDiscoverer.java
+++ b/server/src/com/cloud/hypervisor/xen/discoverer/XcpServerDiscoverer.java
@@ -46,6 +46,7 @@ import com.cloud.dc.ClusterVO;
 import com.cloud.dc.dao.ClusterDao;
 import com.cloud.exception.AgentUnavailableException;
 import com.cloud.exception.ConnectionException;
+import com.cloud.exception.DiscoveredWithErrorException;
 import com.cloud.exception.DiscoveryException;
 import com.cloud.exception.OperationTimedoutException;
 import com.cloud.host.HostEnvironment;
@@ -290,9 +291,8 @@ public class XcpServerDiscoverer extends DiscovererBase implements Discoverer, L
                 resource.start();
                 resources.put(resource, details);
             }                        
-        } catch (SessionAuthenticationFailed e) {
-            s_logger.warn("Authentication error", e);           
-            return null;
+        } catch (SessionAuthenticationFailed e) {       
+            throw new DiscoveredWithErrorException("Authetication error");
         } catch (XenAPIException e) {
             s_logger.warn("XenAPI exception", e);
             return null;
diff --git a/utils/src/com/cloud/utils/SerialVersionUID.java b/utils/src/com/cloud/utils/SerialVersionUID.java
index a1a578fbd67..90be224df8c 100755
--- a/utils/src/com/cloud/utils/SerialVersionUID.java
+++ b/utils/src/com/cloud/utils/SerialVersionUID.java
@@ -62,4 +62,5 @@ public interface SerialVersionUID {
     public static final long sshException = Base | 0x22;
     public static final long HttpCallException = Base | 0x23;
     public static final long VirtualMachineMigrationException = Base | 0x24;
+    public static final long DiscoveredWithErrorException = Base | 0x25;
 }