[HELP} My 1.6.4 Forge 9.11.1.1965 Crash Error

So I've installed Java 7 and changed the directory for Java executable to jre7 folder but gave me 'ERROR: could not create java virtual machine' so I went in googled how to fix it.

I came across that I had to go into environment variables and give _JAVA_OPTIONS with -Xmx512M but it was too small so i made it have 1024M. I am trying to make a server but I have to get the client

working first I figured. When I try to open up 1.6.4 Forge it still gives me the error I wrote above and when I try to run the server .jar file that I got from Forge server installer it gives me:

2017-12-02 14:46:29 [INFO] [ForgeModLoader] Forge Mod Loader version 6.4.49.965 for Minecraft 1.6.4 loading
2017-12-02 14:46:29 [INFO] [ForgeModLoader] Java is Java HotSpot(TM) 64-Bit Server VM, version 1.8.0_151, running on Windows 10:amd64:10.0, installed at C:\Program Files\Java\jre1.8.0_151
2017-12-02 14:46:29 [FINE] [ForgeModLoader] Java classpath at launch is C:\Users\yirang\AppData\Roaming\.minecraft\server\minecraftforge-universal-1.6.4-9.11.1.965-v164-pregradle.jar
2017-12-02 14:46:29 [FINE] [ForgeModLoader] Java library path at launch is C:\Program Files\Java\jre1.8.0_151\bin;C:\WINDOWS\Sun\Java\bin;C:\WINDOWS\system32;C:\WINDOWS;C:\ProgramData\Oracle\Java\javapath;C:\Program Files\Broadcom\Broadcom 802.11 Network Adapter;C:\Program Files (x86)\Intel\iCLS Client\;C:\Program Files\Intel\iCLS Client\;C:\WINDOWS\system32;C:\WINDOWS;C:\WINDOWS\System32\Wbem;C:\WINDOWS\System32\WindowsPowerShell\v1.0\;C:\Program Files\Intel\Intel(R) Management Engine Components\DAL;C:\Program Files (x86)\Intel\Intel(R) Management Engine Components\DAL;C:\Program Files\Intel\Intel(R) Management Engine Components\IPT;C:\Program Files (x86)\Intel\Intel(R) Management Engine Components\IPT;C:\Program Files (x86)\Skype\Phone\;C:\Program Files\Java\jdk-9.0.1\bin;C:\Program Files\Java\jre7;.
2017-12-02 14:46:29 [FINE] [ForgeModLoader] Enabling runtime deobfuscation
2017-12-02 14:46:29 [FINE] [ForgeModLoader] Instantiating coremod class FMLCorePlugin
2017-12-02 14:46:29 [FINE] [ForgeModLoader] Enqueued coremod FMLCorePlugin
2017-12-02 14:46:29 [FINE] [ForgeModLoader] Instantiating coremod class FMLForgePlugin
2017-12-02 14:46:29 [FINE] [ForgeModLoader] Enqueued coremod FMLForgePlugin
2017-12-02 14:46:29 [FINE] [ForgeModLoader] All fundamental core mods are successfully located
2017-12-02 14:46:29 [FINE] [ForgeModLoader] Discovering coremods
2017-12-02 14:46:29 [INFO] [ForgeModLoader] Loading tweak class name cpw.mods.fml.common.launcher.FMLInjectionAndSortingTweaker
2017-12-02 14:46:29 [INFO] [ForgeModLoader] Loading tweak class name cpw.mods.fml.common.launcher.FMLDeobfTweaker
2017-12-02 14:46:29 [INFO] [ForgeModLoader] Calling tweak class cpw.mods.fml.common.launcher.FMLInjectionAndSortingTweaker
2017-12-02 14:46:29 [SEVERE] [ForgeModLoader] Unable to launch
java.util.ConcurrentModificationException
    at java.util.ArrayList$Itr.checkForComodification(Unknown Source)
    at java.util.ArrayList$Itr.remove(Unknown Source)
    at net.minecraft.launchwrapper.Launch.launch(Launch.java:114)
    at net.minecraft.launchwrapper.Launch.main(Launch.java:27)
    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 cpw.mods.fml.relauncher.ServerLaunchWrapper.run(ServerLaunchWrapper.java:48)
    at cpw.mods.fml.relauncher.ServerLaunchWrapper.main(ServerLaunchWrapper.java:17)
 

I also set the PATH in user variables pointing to JRE7 File. I want to fix both errors so I can run the client (singleplayer) and to get the server working.