Minecraft Forums

so I had to force update minecraft right? and randomly... my minecraft crashed!, so, I reopened it and now it just loads up, then stops at done loading, I checked my terminal, here: (I can't read java, please help!)(and oh yeah, I was using magic launcher)

***MagicMinecraftLauncher 0.9.9 ***
java.lang.NoClassDefFoundError: aiz
at java.lang.Class.getDeclaredMethods0(Native Method)
at java.lang.Class.privateGetDeclaredMethods(Class.java:2427)
at java.lang.Class.getMethod0(Class.java:2670)
at java.lang.Class.getMethod(Class.java:1603)
at magic.launcher.Launcher.main(Unknown Source)
Caused by: java.lang.ClassNotFoundException: aiz
at java.net.URLClassLoader$1.run(URLClassLoader.java:202)
at java.security.AccessController.doPrivileged(Native Method)
at java.net.URLClassLoader.findClass(URLClassLoader.java:190)
at java.lang.ClassLoader.loadClass(ClassLoader.java:306)
at sun.misc.Launcher$AppClassLoader.loadClass(Launcher.java:301)
at java.lang.ClassLoader.loadClass(ClassLoader.java:247)
... 5 more

I would try to delete your bin folder and then Force Update your Minecraft.

Try to delete your minecraft.jar and all your .jar files and force update. If it deletes your worlds, try to make back-ups. Save everything until you are satisfied with your Minecraft.jar and if its working.