The login screen comes up, but when attempting to login, an error occurs.

Error:  An unexpected error has occurred. Contact your system administrator if this problem persists.

There may be errors in the Manager.properties file (located at \SymantecDLP\Protect\config) regarding the syslog entries.

Errors in the Tomcat\localhost.yyyy-mm-dd.log:

31 May 2018 08:48:39,889- Thread: 18 SEVERE [com.vontu.manager.ProtectServlet] (MANAGER.3) An error occurred during the startup of the Manager service
Cause:
javax.servlet.ServletException: Error initializing system event command runtime
com.vontu.command.loader.CommandRuntimeLoaderException: Error creating CommandRutnime.
com.vontu.command.CommandRuntimeException: Error initializing command: syslog (ID -2147483648).
java.lang.NumberFormatException: For input string: "{hostname fqdn}"
javax.servlet.ServletException: Error initializing system event command runtime
    at com.vontu.manager.init.InitSystemEventCommands.loadCommandRuntime(InitSystemEventCommands.java:95)
    at com.vontu.manager.init.InitSystemEventCommands.init(InitSystemEventCommands.java:60)
    at com.vontu.manager.init.ServletInitTaskManager.init(ServletInitTaskManager.java:123)
    at com.vontu.manager.ProtectServlet.init(ProtectServlet.java:155)
    at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
    at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:62)
    at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
    at java.lang.reflect.Method.invoke(Method.java:498)
    at org.apache.catalina.security.SecurityUtil$1.run(SecurityUtil.java:288)
    at org.apache.catalina.security.SecurityUtil$1.run(SecurityUtil.java:285)
    at java.security.AccessController.doPrivileged(Native Method)
    at javax.security.auth.Subject.doAsPrivileged(Subject.java:549)
    at org.apache.catalina.security.SecurityUtil.execute(SecurityUtil.java:320)
    at org.apache.catalina.security.SecurityUtil.doAsPrivilege(SecurityUtil.java:175)
    at org.apache.catalina.security.SecurityUtil.doAsPrivilege(SecurityUtil.java:124)
    at org.apache.catalina.core.StandardWrapper.initServlet(StandardWrapper.java:1257)
    at org.apache.catalina.core.StandardWrapper.loadServlet(StandardWrapper.java:1182)
    at org.apache.catalina.core.StandardWrapper.load(StandardWrapper.java:1072)
    at org.apache.catalina.core.StandardContext.loadOnStartup(StandardContext.java:5368)
    at org.apache.catalina.core.StandardContext.startInternal(StandardContext.java:5660)
    at org.apache.catalina.util.LifecycleBase.start(LifecycleBase.java:145)
    at org.apache.catalina.core.ContainerBase.addChildInternal(ContainerBase.java:899)
    at org.apache.catalina.core.ContainerBase.access$000(ContainerBase.java:133)
    at org.apache.catalina.core.ContainerBase$PrivilegedAddChild.run(ContainerBase.java:156)
    at org.apache.catalina.core.ContainerBase$PrivilegedAddChild.run(ContainerBase.java:145)
    at java.security.AccessController.doPrivileged(Native Method)
    at org.apache.catalina.core.ContainerBase.addChild(ContainerBase.java:873)
    at org.apache.catalina.core.StandardHost.addChild(StandardHost.java:652)
    at org.apache.catalina.startup.HostConfig.deployDirectory(HostConfig.java:1260)
    at org.apache.catalina.startup.HostConfig$DeployDirectory.run(HostConfig.java:2002)
    at java.util.concurrent.Executors$RunnableAdapter.call(Executors.java:511)
    at java.util.concurrent.FutureTask.run(FutureTask.java:266)
    at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1142)
    at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:617)
    at java.lang.Thread.run(Thread.java:748)
Caused by: com.vontu.command.loader.CommandRuntimeLoaderException: Error creating CommandRutnime.
    at com.vontu.command.loader.CommandRuntimeLoader.load(CommandRuntimeLoader.java:109)
    at com.vontu.command.loader.ModelCommandRuntimeLoader.load(ModelCommandRuntimeLoader.java:109)
    at com.vontu.manager.init.InitSystemEventCommands.loadCommandRuntime(InitSystemEventCommands.java:80)
    ... 34 more
Caused by: com.vontu.command.CommandRuntimeException: Error initializing command: syslog (ID -2147483648).
    at com.vontu.command.CommandRuntime.initializeCommandRuntimeInstructions(CommandRuntime.java:468)
    at com.vontu.command.CommandRuntime.start(CommandRuntime.java:569)
    at com.vontu.command.loader.CommandRuntimeLoader.load(CommandRuntimeLoader.java:102)
    ... 36 more
Caused by: java.lang.NumberFormatException: For input string: "FQDN"
    at java.lang.NumberFormatException.forInputString(NumberFormatException.java:65)
    at java.lang.Integer.parseInt(Integer.java:580)
    at java.lang.Integer.parseInt(Integer.java:615)
    at com.vontu.manager.command.systemevent.SyslogLogger.initialize(SyslogLogger.java:73)
    at com.vontu.command.Instruction.initialize(Instruction.java:82)
    at com.vontu.command.CommandRuntime.initializeCommandRuntimeInstructions(CommandRuntime.java:457)
    ... 38 more

Check the information in the Manager.properties file and make necessary corrections:
com.vontu.manager.system.statistics.StatisticsRollup.period = 86400000
systemevent.syslog.host = {hostname fqdn}
systemevent.syslog.port = 514

After the settings are corrected, recycle the SymantecDLPManager service, and login.