I'm getting an Unable to Launch error, tried reinstalling the launcher, reinstalling the modpack... nothing seems to help. I appended the log:
Code:AnalyticsBackgroundThread started FTBLaunch starting up (version 1.4.12 Build: 10412) OS: Windows 10 10.0 (64-bit) Launcher Install Dir: B:\Feed The Beast System memory: 11308M free, 14221M total The FTB Launcher has found the following Java versions installed: Java Version: 1.8.0_91 sorted as: 1.8.0_91 32 Bit Java at : C:\Program Files (x86)\Java\jre1.8.0_91\bin\java.exe Java Version: 1.8.0_92 sorted as: 1.8.0_92 32 Bit Java at : C:\Program Files (x86)\Java\jre1.8.0_92\bin\java.exe Java Version: 1.8.0_91 sorted as: 1.8.0_91 64 Bit Java at : C:\Program Files\Java\jre1.8.0_91\bin\java.exe Java Version: 1.8.0_91 sorted as: 1.8.0_91 64 Bit Java at : C:\Program Files\Java\jre1.8.0_91\bin\java.exe Preferred: Java Version: 1.8.0_91 sorted as: 1.8.0_91 64 Bit Java at : C:\Program Files\Java\jre1.8.0_91\bin\java.exe [i18n] Fallback enUS loaded [i18n] enUS English (US) language file loaded! Checking installation location Loading user data Using download server CurseCDN:CurseCDN on host ftb.cursecdn.com (104.16.15.166) Creating Console window Creating main window [i18n] Added 0 enUS to options pane [i18n] Added 1 cyGB to options pane [i18n] Added 2 daDK to options pane [i18n] Added 3 deDE to options pane [i18n] Added 4 enGB to options pane [i18n] Added 5 enUS to options pane [i18n] Added 6 esES to options pane [i18n] Added 7 fiFI to options pane [i18n] Added 8 frCA to options pane [i18n] Added 9 frFR to options pane [i18n] Added 10 itIT to options pane [i18n] Added 11 maHU to options pane [i18n] Added 12 nlNL to options pane [i18n] Added 13 noNO to options pane [i18n] Added 14 plPL to options pane [i18n] Added 15 ptBR to options pane [i18n] Added 16 ptPT to options pane [i18n] Added 17 ruRU to options pane [i18n] Added 18 svSE to options pane [i18n] Added 19 zhCN to options pane [i18n] enUS English (US) language file loaded! Setting up Launcher Downloading pack data Local Authlib Version is good, skipping Download Adding Authlib to Classpath Loading modpack information for obscurity.xml... Loading modpack information for thirdparty.xml... Loading modpack information for modpacks.xml... Loading modpack information for technofirma.xml... loading map information... loading texture pack information... Opening main window Adding texture pack 1 (Soartex Fanver) Adding texture pack 2 (Jadedcat Mixpack) Adding texture pack 3 (Invictus) Adding texture pack 4 (Faithful) Adding texture pack 5 (JohnSmith Technicians Remix) Adding texture pack 6 (Familiar yet Different) Adding map 1 (FTB Trident Default Map) Adding map 2 (Agrarian Skies Default Map) Adding map 3 (Agrarian Skies Flat Map) Adding map 4 (Agrarian Skies Server Map) Adding map 5 (Direwolf20 Map Ep.0) Adding map 6 (FTB Pax Challenge) Adding map 7 (Direwolf20 Map Ep.0) Adding map 8 (Direwolf20 Map Ep.10) Adding map 9 (Direwolf20 Map Ep.20) Adding map 10 (Direwolf20 Map Ep.30) Adding map 11 (Direwolf20 Map Ep.40) Adding map 12 (Direwolf20 Map Ep.50) Adding map 13 (Direwolf20 Map Ep.80) Adding map 14 (FTB Normal) Adding map 15 (FTB Insanity) MCVersion: 1710 Logging in... Beginning authlib authentication attempt successfully created YggdrasilAuthenticationService Login complete. InfiTech2 Downloading Mod Pack Issue with new md5 method, attempting to use backup method. Local: B3E6DB7BB36CDE869A7AADFFD0D6356C Remote: B3E6DB7BB36CDE869A7AADFFD0D6356C Mods Folder: B:\Feed The Beast\InfiTech2\minecraft\mods Dynamic Folder: C:\Users\Joshua\AppData\Local\ftblauncher\ModPacks\InfiTech2\minecraft\mods dirs mk'd Checking local assets file, for MC version 1.7.10 Please wait! Setting up native libraries for InfiTech 2 v Recommended Version MC 1.7.10 Syncing Assets: Java Path: C:\Program Files\Java\jre1.8.0_91\bin\javaw.exe Pack: InfiTech 2 1.7.10 Setting MinMemory to 256 Setting MaxMemory to 8192 Adding Optimization Arguments: -XX:+UseParNewGC -XX:+UseConcMarkSweepGC -XX:+CICompilerCountPerCPU -XX:+TieredCompilation [16:17:37] [main/INFO]: Loading tweak class name cpw.mods.fml.common.launcher.FMLTweaker [16:17:37] [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:?]
have you tried using the curse launcher? im not sure but seems to be an issue with either the launcher or the mods in the one your downloading... try selecting a lower version of the pack and going to the next one. instead of using recommended. thats fixed random launcher crashes for me. hope someone else could be of more help.