Cann't open spark in multi-user server

My Openfire 3.6.4 running in Windows 2003 standard sever A, the client is Spark 2.5.8 running in Windows 2003 standard Server B. Sever B is an

multi-user terminal server. ref this link:

Most of the time, 10 spark users work normally in server B. But some time, for example 3 user work normally,and other 7 users cann’t open spark.exe any more. I have to clear all the 3 user’s spark.exe in task manager,and then spark will be work fine. Some time it will be show this error:

java.lang.NoClassDefFoundError: de/javasoft/plaf/synthetica/SyntheticaBlueMoonLookAndFeel

at java.lang.Class.getDeclaredConstructors0(Native Method)

at java.lang.Class.privateGetDeclaredConstructors(Unknown Source)

at java.lang.Class.getConstructor0(Unknown Source)

at java.lang.Class.newInstance0(Unknown Source)

at java.lang.Class.newInstance(Unknown Source)

at org.jivesoftware.launcher.Startup.start(

at org.jivesoftware.launcher.Startup.main(

at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)

at sun.reflect.NativeMethodAccessorImpl.invoke(Unknown Source)

at sun.reflect.DelegatingMethodAccessorImpl.invoke(Unknown Source)

at java.lang.reflect.Method.invoke(Unknown Source)

at com.exe4j.runtime.LauncherEngine.launch(Unknown Source)

at com.exe4j.runtime.WinLauncher.main(Unknown Source)

I don’t know Why?

Maybe you want to try the latest Spark client? 2.5.8 is pretty old and does not have any support.