Occasionally, the situation and error messages available to you do not point to a particular problem and resolution. Thus, it can be helpful to check the health of a module—in this case, Talend JobServer.
Use the following checklist to troubleshoot JobServer. Each of these individual steps might fix your issue—you do not have to do them in order.
Are you using two TACs, in High Availability mode? If so, and you are using a virtual server, make sure the JobServers all point to the same shared folder/directory where the Jobs are stored. This directory is specified in the TAC > Configuration > Job Conductor > Generated Jobs folder.
Are you communicating with the JobServer over SSL? Check the SSL configuration.
Is there a proxy or firewall between TAC and JobServer? Ensure you can connect to the JobServer from the TAC server. To do this, try to telnet from the TAC machine to the JobServer machine, for example, telnet jobserver_host 8001. A blank/black screen means you are connected, and nothing (proxy/firewall) is blocking your access. If running this command hangs without seeming to do anything (the telnet... command text does not disappear from your terminal), then you may have a proxy or firewall blocking access—so you need to set the proxy parameters on TAC. For more information on installing telnet, see the Telnet is not recognized as an internal or external command, operable program, or batch file article in the Talend Community Knowledge Base (KB).
Restart the JobServer. Windows: Restart the service from the Services applet in Control Panel. On Unix/Linux, service stop talend-rjs-6.4.1 (rjs stands for Remote JobServer).
Verify that the TAC server/service user has full permissions in the [JobServerHome] directory structure.
Can you start JobServer manually, by using C:\Talend\6.4.1\jobserver\start_jobserver.bat, versus starting it as a service? This can affect permissions.
Make sure JobServer is running, for example, telnet cmdline_host 8000 (the JobServer default Command Port is 8000). If you get a blank/black screen, it is running. If you get a Connection refused error message, then the JobServer is not running.
Set the following line in the TalendJobServer.properties file to the path of the Java.exe executable (Windows) or Java (*nix)—because the Java executable may not be in the %PATH% (Unix: $PATH) of the JobServer user/server/service.
Check that the JAVA_HOME environment variable is pointing to Java version 1.8.x (not 1.7 or 1.9).
Check that Java -version and "%JAVA_HOME%"\bin\java -version" reports are set to version 1.8.x (on Unix/Linux: $JAVA_HOME/bin/java -version).
Ensure that the execution path of the service (in Windows from the Services applet in Control Panel) is pointing to the same %JAVA_HOME% path.
Make sure that the TAC > Menu > Configuration > Job Conductor > Generated Jobs and TAC > Menu > Configuration > Job Conductor > Tasks log folders exist and are writable by JobServer.
Ensure that the TAC > Menu > Configuration > CommandLine/primary > Job Generation folder path exists and is writable by the CommandLine server.