Launcher will not launch the game.

[zacman003]

I tried to launch FTB Unleashed, and I got an error. It gives me the same error no matter which mod pack I attempt to use. Here is the error I receive.

[13:18:50] [ERROR] ClassLoader.checkCerts:806->MinecraftLauncher.main:217: Unhandled error launching minecraft: java.lang.SecurityException: class "sq"'s signer information does not match signer information of other classes in the same package
java.lang.ClassLoader.checkCerts(ClassLoader.java:806)
java.lang.ClassLoader.preDefineClass(ClassLoader.java:487)
java.lang.ClassLoader.defineClassCond(ClassLoader.java:625)
java.lang.ClassLoader.defineClass(ClassLoader.java:615)
java.security.SecureClassLoader.defineClass(SecureClassLoader.java:141)
java.net.URLClassLoader.defineClass(URLClassLoader.java:283)
java.net.URLClassLoader.access$000(URLClassLoader.java:58)
java.net.URLClassLoader$1.run(URLClassLoader.java:197)
java.security.AccessController.doPrivileged(Native Method)
java.net.URLClassLoader.findClass(URLClassLoader.java:190)
java.lang.ClassLoader.loadClass(ClassLoader.java:306)
sun.misc.Launcher$AppClassLoader.loadClass(Launcher.java:301)
java.lang.ClassLoader.loadClass(ClassLoader.java:247)
java.lang.Class.getDeclaredFields0(Native Method)
java.lang.Class.privateGetDeclaredFields(Class.java:2339)
java.lang.Class.getDeclaredFields(Class.java:1770)
net.ftb.mclauncher.MinecraftLauncher.main(MinecraftLauncher.java:185)

Following this error, the launcher freezes.

Thanks in advanced,

(On mac by the way)

 

[lavarthan]

Check your log in. I've helped another user with a similar error and he was trying to play minecraft without paying for it first. You are required to have a premium minecraft log in to play FTB.

If you have paid then follow this guide to reinstall the launcher from scratch the recommended way. After that if you are still experiencing problems please post a full console log to pastebin.com and link to it here. This guide will help you with the logs.

Edit: Also mojang has been having trouble with the log in servers recently.