Bug My FTB is not lauching

[urban_scrambled]

I have tried launching FTB Infinity Evolved 1.7 (v2.5.0) Minecraft Version 1.7.10 but in my log is says that it was unable to launch. Below is what it was saying in my log. I would appreciate some help thanks.

Logging in...
Beginning authlib authentication attempt
successfully created YggdrasilAuthenticationService
Login complete.
Checking local assets file, for MC version 1.7.10 Please wait!
Setting up native libraries for FTB Infinity Evolved 1.7 v Recommended Version MC 1.7.10
Syncing Assets:
Java Path: C:\Program Files\Java\jre1.8.0_91\bin\javaw.exe
Pack: FTB Infinity Evolved 1.7 1.7.10
Setting MinMemory to 256
Setting MaxMemory to 2048
[14:17:23] [main/INFO]: Loading tweak class name cpw.mods.fml.common.launcher.FMLTweaker
[14:17:23] [main/ERROR]: Unable to launch
java.lang.ClassNotFoundException: cpw.mods.fml.common.launcher.FMLTweaker
at java.net.URLClassLoader.findClass(Unknown Source) ~[?:1.8.0_91]
at java.lang.ClassLoader.loadClass(Unknown Source) ~[?:1.8.0_91]
at sun.misc.Launcher$AppClassLoader.loadClass(Unknown Source) ~[?:1.8.0_91]
at java.lang.ClassLoader.loadClass(Unknown Source) ~[?:1.8.0_91]
at net.minecraft.launchwrapper.LaunchClassLoader.findClass(LaunchClassLoader.java:106) ~[launchwrapper-1.12.jar:?]
at java.lang.ClassLoader.loadClass(Unknown Source) ~[?:1.8.0_91]
at java.lang.ClassLoader.loadClass(Unknown Source) ~[?:1.8.0_91]
at java.lang.Class.forName0(Native Method) ~[?:1.8.0_91]
at java.lang.Class.forName(Unknown Source) ~[?:1.8.0_91]
at net.minecraft.launchwrapper.Launch.launch(Launch.java:98) [launchwrapper-1.12.jar:?]
at net.minecraft.launchwrapper.Launch.main(Launch.java:28) [launchwrapper-1.12.jar:?]

 

[tofuturkey]

I'm having the same issue. A google search turns up half a dozen different possible fixes, none of which are remotely similar and none seem to help my particular problem. I've reinstalled Java, reinstalled the FTB launcher, tried to use (for the very first time, fresh install) the Curse launcher, I keep getting the same error. Is this related to this version of Java perhaps? I'm somewhat surprised there aren't more of these cropping up. Help would be very much appreciated; the normal "just reinstall it" routine isn't working, which means I literally will never be able to play FTB again...

 

[jikuja]

Related with antivirus products or firewalls usually. check those and reinstall instance.

 

[tofuturkey]

On the Curse Launcher (don't know if you can help with that here), I deactivated all my antivirus, including built-in Microsoft crapware, no dice. The new instance appears identical to the old one, and gives the same error.

Interestingly enough, this did work with the FTB launcher. Tried starting from scratch on the Curse launcher, nothing.

 

[Prof_SuperChaser]

I have the same issue and it is really frustrating me, please can someone help

 

[EODCrafter]

Just a thought, Try installing Java 7 alongside Java 8. Maybe a Dev is still in the Dark Ages .