FTB launch error

[superlewis]

Title:

FTB launch error​

Launcher Version:

1.4.8​

Modpack:

direwolf20​

Modpack Version:

1.7.10​

Log Link:

​

Details of the issue:

[main/ERROR]: Unable to launch
java.lang.ClassNotFoundException: cpw.mods.fml.common.launcher.FMLTweaker
at java.net.URLClassLoader.findClass(Unknown Source) ~[?:1.8.0_60]
at java.lang.ClassLoader.loadClass(Unknown Source) ~[?:1.8.0_60]
at sun.misc.Launcher$AppClassLoader.loadClass(Unknown Source) ~[?:1.8.0_60]
at java.lang.ClassLoader.loadClass(Unknown Source) ~[?:1.8.0_60]
at net.minecraft.launchwrapper.LaunchClassLoader.findClass(LaunchClassLoader.java:106) ~[launchwrapper-1.11.jar:?]
at java.lang.ClassLoader.loadClass(Unknown Source) ~[?:1.8.0_60]
at java.lang.ClassLoader.loadClass(Unknown Source) ~[?:1.8.0_60]
at java.lang.Class.forName0(Native Method) ~[?:1.8.0_60]
at java.lang.Class.forName(Unknown Source) ~[?:1.8.0_60]
at net.minecraft.launchwrapper.Launch.launch(Launch.java:98) [launchwrapper-1.11.jar:?]
at net.minecraft.launchwrapper.Launch.main(Launch.java:28) [launchwrapper-1.11.jar:?]​

 

[jikuja]

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