Wont start the game up/Keeps crashing

[SuperNateHD]

Title:

Wont start the game up/Keeps crashing​

Launcher Version:

1.4.8​

Modpack:

Direwolf20​

Modpack Version:

Latest i guess​

Log Link:

http://pastebin.com/Kq2dPVdW​

Details of the issue:

This is at least what i think causes the crash.
[13:26:02] [main/INFO] [STDERR]: [java.lang.Throwable$WrappedPrintStreamrintln:-1]: java.lang.NoClassDefFoundError: scala/collection/Seq
[13:26:02] [main/INFO] [STDERR]: [java.lang.Throwable$WrappedPrintStreamrintln:-1]: at java.lang.Class.forName0(Native Method)
[13:26:02] [main/INFO] [STDERR]: [java.lang.Throwable$WrappedPrintStreamrintln:-1]: at java.lang.Class.forName(Unknown Source)
[13:26:02] [main/INFO] [STDERR]: [java.lang.Throwable$WrappedPrintStreamrintln:-1]: at cpw.mods.fml.relauncher.CoreModManager.loadCoreMod(CoreModManager.java:417)
[13:26:02] [main/INFO] [STDERR]: [java.lang.Throwable$WrappedPrintStreamrintln:-1]: at​

 

[jikuja]

On the launcher go to options then click the force update button, then launch the modpack.