2818099 - Error: "Could not connect to Deploy Controller" during DEPLOY-SHADOW-INSTANCE phase

During the upgrade of a SAP NetWeaver AS Java system, the following error occurs during DEPLOY-SHADOW-INSTANCE phase:

Overal deployment message : Could not connect to Deploy Controller. Make sure that AS Java and Deploy Controller service are running.
com.sap.engine.services.dc.api.ConnectionException: [ERROR CODE DPL.DCAPI.1144] Could not establish connection to AS Java on [sapsolman:50304]. Connection refused: connect (local port 50252 to address 0.0.0.0, remote port 50304 to address (IP address) (host)). Check if the host and port specified are correct and AS Java is up and running.
javax.naming.NamingException: Exception while trying to get InitialContext. [Root exception is com.sap.engine.interfaces.cross.DestinationException: Cannot establish connection with any of the available profiles. Check if server is started, access point for the protocol is available, and IP/Host name is accessible on the network. 
URL=sapsolman:50304, protocol=p4(None), Reason: com.sap.engine.services.rmi_p4.P4IOException: Cannot open connection to host: (IP address) and port: 50304;]
com.sap.engine.interfaces.cross.DestinationException: Cannot establish connection with any of the available profiles. Check if server is started, access point for the protocol is available, and IP/Host name is accessible on the network.

• SAP NetWeaver 7.x

DPL.DCAPI.1144, Make sure that AS Java and Deploy Controller service are running, P4IOException: Cannot open connection to host, DestinationException: Cannot establish connection with any of the available profiles, SUM, NW Java, SAP Netweaver

P4IOException: Cannot open connection to host