hello,
im useing last version of forge on minecraft 1.12.2(there's a lot of performance issues on higher versions so we developing on this version,so changeing to a newer version is a problem for us ,will be happy if there's another solution )
we made a mod using intelliJ ,now im trying to test it on the server ,
so im putting as part of the arguments my username and password in runClient(if username and incorrect i do get a different msg saying it )
but i get an error,this one,when im trying to lanch the game from the IDE intelliJ with the username and password: 

java.lang.NullPointerException: null
	at net.minecraftforge.fml.common.launcher.Yggdrasil.login(Yggdrasil.java:55) ~[forge-1.12.2-14.23.5.2855_mapped_snapshot_20171003-1.12-recomp.jar:?]
	at net.minecraftforge.fml.common.launcher.FMLTweaker.acceptOptions(FMLTweaker.java:123) ~[forge-1.12.2-14.23.5.2855_mapped_snapshot_20171003-1.12-recomp.jar:?]
	at net.minecraft.launchwrapper.Launch.launch(Launch.java:114) [launchwrapper-1.12.jar:?]
	at net.minecraft.launchwrapper.Launch.main(Launch.java:28) [launchwrapper-1.12.jar:?]
	at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method) ~[?:1.8.0_181]
	at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:62) ~[?:1.8.0_181]
	at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43) ~[?:1.8.0_181]
	at java.lang.reflect.Method.invoke(Method.java:498) ~[?:1.8.0_181]
	at net.minecraftforge.legacydev.Main.start(Main.java:86) [legacydev-0.2.3.1-fatjar.jar:0.2.3.1+4+372be23]
	at net.minecraftforge.legacydev.MainClient.main(MainClient.java:29) [legacydev-0.2.3.1-fatjar.jar:0.2.3.1+4+372be23]
Exception in thread "main" java.lang.reflect.InvocationTargetException
	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 net.minecraftforge.legacydev.Main.start(Main.java:86)
	at net.minecraftforge.legacydev.MainClient.main(MainClient.java:29)
Caused by: net.minecraftforge.fml.relauncher.FMLSecurityManager$ExitTrappedException
	at net.minecraftforge.fml.relauncher.FMLSecurityManager.checkPermission(FMLSecurityManager.java:49)
	at java.lang.SecurityManager.checkExit(SecurityManager.java:761)
	at java.lang.Runtime.exit(Runtime.java:107)
	at java.lang.System.exit(System.java:971)
	at net.minecraft.launchwrapper.Launch.launch(Launch.java:138)
	at net.minecraft.launchwrapper.Launch.main(Launch.java:28)
	... 6 more

 

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