2752110 - Diagnostics Agent disconnected with error: java.lang.IllegalArgumentException: reconfigure agent connection failed, unknown protocol type: -1

• You are trying to connect the agent but the agent is not shown in the Agent Adminitration.
• In the SMDSystem.log you will find the following error stack:

Error [Exception ID: 1549629574128 ] com.sap.smd.agent.bootstrap.BootstrapException
[EXCEPTION]
com.sap.smd.agent.bootstrap.BootstrapException: com.sap.smd.om.ObjectLoadException: error during load [while trying to load object entities:com.sap.smd.agent.application.runtime.SMDPluginService]
 at com.sap.smd.core.runtime.broker.ApplicationManager.reachInitializationStates(ApplicationManager.java:348)
 at com.sap.smd.core.runtime.Runtime.run(Runtime.java:57)
 at com.sap.smd.agent.SMDAgeletsRuntimeContext.runStarterPlugin(SMDAgeletsRuntimeContext.java:111)
 at com.sap.smd.agent.SMDAgeletsRuntimeContext.startApplications(SMDAgeletsRuntimeContext.java:162)
 at com.sap.smd.agent.AgentContext.startApplications(AgentContext.java:775)
 at com.sap.smd.agent.SMDAgeletsRuntimeContext.offlineStart(SMDAgeletsRuntimeContext.java:484)
 at com.sap.smd.agent.SMDAgeletsRuntimeContext.offlineStartAppsIfNeeded(SMDAgeletsRuntimeContext.java:377)
 at com.sap.smd.agent.SMDAgeletsRuntimeContext.statusChanged(SMDAgeletsRuntimeContext.java:334)
 at com.sap.smd.agent.connection.SMDConnector.triggerStatusChanged(SMDConnector.java:966)
 at com.sap.smd.agent.connection.SMDConnector.setConnectionStatus(SMDConnector.java:886)
 at com.sap.smd.agent.connection.SMDConnectionTask.startOffline(SMDConnectionTask.java:980)
 at com.sap.smd.agent.connection.SMDConnectionTask.internalAttemptConnection(SMDConnectionTask.java:594)
 at com.sap.smd.agent.connection.SMDConnectionTask$1.run(SMDConnectionTask.java:111)
 at com.sap.smd.agent.connection.P4JNDIContextHelper.executeInSecurityContext(P4JNDIContextHelper.java:146)
 at com.sap.smd.agent.connection.SMDConnectionTask.attemptConnection(SMDConnectionTask.java:106)
 at com.sap.smd.agent.connection.SMDConnectionTask.run(SMDConnectionTask.java:1460)
 at java.lang.Thread.run(Thread.java:836)
Caused by: com.sap.smd.om.ObjectLoadException: error during load [while trying to load object entities:com.sap.smd.agent.application.runtime.SMDPluginService]
 at com.sap.smd.om.impl.broker.ObjectProxyImpl.loadInternal(ObjectProxyImpl.java:336)
 at com.sap.smd.om.impl.broker.ObjectReference.loadDependencies(ObjectReference.java:305)
 at com.sap.smd.om.impl.broker.ObjectProxyImpl.loadInternal(ObjectProxyImpl.java:272)
 at com.sap.smd.om.impl.broker.ObjectProxyImpl.load(ObjectProxyImpl.java:146)
 at com.sap.smd.core.runtime.broker.ApplicationManager.loadState(ApplicationManager.java:468)
 at com.sap.smd.core.runtime.broker.ApplicationManager.reachInitializationStates(ApplicationManager.java:326)
 ... 16 more
Caused by: java.lang.IllegalArgumentException: reconfigure agent connection failed, unknown protocol type: -1
 at com.sap.smd.core.runtime.agent.ConnectionPropertyChangeListener.getTargetPort(ConnectionPropertyChangeListener.java:149)
 at com.sap.smd.core.runtime.agent.ConnectionPropertyChangeListener.adjustAgentConnectionUrlSetting(ConnectionPropertyChangeListener.java:60)
 at com.sap.smd.core.runtime.agent.ConnectionPropertyChangeListener.checkOfflinePropertyChange(ConnectionPropertyChangeListener.java:100)
 at com.sap.smd.core.runtime.agent.SMDAgentService.init(SMDAgentService.java:109)
 at com.sap.smd.core.plugin.service.ServiceEntityHandle.entityLoad(ServiceEntityHandle.java:114)
 at com.sap.smd.core.runtime.broker.application.api.entity.AbstractEntityHandle.load(AbstractEntityHandle.java:234)
 at com.sap.smd.core.runtime.broker.application.core.entity.PseudoEntityHandle.load(PseudoEntityHandle.java:154)
 at com.sap.smd.om.impl.broker.ObjectProxyImpl.loadInternal(ObjectProxyImpl.java:308)
 ... 21 more

Diagnostics agent connecting with SAP Solution Manager

Diagnostics Agent, unknown protocol type: -1, ConnectionPropertyChangeListener , KBA , SV-SMG-DIA-SRV-AGT , Agent Framework , Problem