Minecraft Forums

hello guys.

Im triying to play a modpack called MUNDOL3TCRAFT (it's a modpack used in a series of some spanish youtubers) and im triying to install it through curse voice. Everything seems fine and it finishes downloading, but when i try to play it this error occurs:

[19:54:05] [main/INFO]: Loading tweak class name cpw.mods.fml.common.launcher.FMLTweaker
[19:54:05] [main/ERROR]: Unable to launch
java.lang.ClassNotFoundException: cpw.mods.fml.common.launcher.FMLTweaker
at java.net.URLClassLoader$1.run(URLClassLoader.java:372) ~[?:1.8.0_25]
at java.net.URLClassLoader$1.run(URLClassLoader.java:361) ~[?:1.8.0_25]
at java.security.AccessController.doPrivileged(Native Method) ~[?:1.8.0_25]
at java.net.URLClassLoader.findClass(URLClassLoader.java:360) ~[?:1.8.0_25]
at java.lang.ClassLoader.loadClass(ClassLoader.java:424) ~[?:1.8.0_25]
at sun.misc.Launcher$AppClassLoader.loadClass(Launcher.java:308) ~[?:1.8.0_25]
at java.lang.ClassLoader.loadClass(ClassLoader.java:357) ~[?:1.8.0_25]
at net.minecraft.launchwrapper.LaunchClassLoader.findClass(LaunchClassLoader.java:106) ~[launchwrapper-1.11.jar:?]
at java.lang.ClassLoader.loadClass(ClassLoader.java:424) ~[?:1.8.0_25]
at java.lang.ClassLoader.loadClass(ClassLoader.java:357) ~[?:1.8.0_25]
at java.lang.Class.forName0(Native Method) ~[?:1.8.0_25]
at java.lang.Class.forName(Class.java:344) ~[?:1.8.0_25]
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:?]
Java HotSpot(TM) 64-Bit Server VM warning: ignoring option PermSize=256m; support was removed in 8.0

Im desperate and don't know what else to do. im triying to use cursevoice because the people that made the pack there have a dedicated server to the modpack.

Please help guys.

By the way, im using java 7u80 to avoid problems. tried to unmark the JVM arguments if that was the problem and the error changed, this was in there:

-Xmx4096m -Xms256m -XX:PermSize=256m -Dminecraft.applet.TargetDirectory="C:\Users\ggioop\Documents\Curse\Minecraft\Instances\MUNDO L3TCRAFT" -Dfml.ignorePatchDiscrepancies=true -Dfml.ignoreInvalidMinecraftCertificates=true

now this is the error:

[20:03:46] [main/INFO]: Loading tweak class name cpw.mods.fml.common.launcher.FMLTweaker
[20:03:46] [main/ERROR]: Unable to launch
java.lang.ClassNotFoundException: cpw.mods.fml.common.launcher.FMLTweaker
at java.net.URLClassLoader$1.run(URLClassLoader.java:372) ~[?:1.8.0_25]
at java.net.URLClassLoader$1.run(URLClassLoader.java:361) ~[?:1.8.0_25]
at java.security.AccessController.doPrivileged(Native Method) ~[?:1.8.0_25]
at java.net.URLClassLoader.findClass(URLClassLoader.java:360) ~[?:1.8.0_25]
at java.lang.ClassLoader.loadClass(ClassLoader.java:424) ~[?:1.8.0_25]
at sun.misc.Launcher$AppClassLoader.loadClass(Launcher.java:308) ~[?:1.8.0_25]
at java.lang.ClassLoader.loadClass(ClassLoader.java:357) ~[?:1.8.0_25]
at net.minecraft.launchwrapper.LaunchClassLoader.findClass(LaunchClassLoader.java:106) ~[launchwrapper-1.11.jar:?]
at java.lang.ClassLoader.loadClass(ClassLoader.java:424) ~[?:1.8.0_25]
at java.lang.ClassLoader.loadClass(ClassLoader.java:357) ~[?:1.8.0_25]
at java.lang.Class.forName0(Native Method) ~[?:1.8.0_25]
at java.lang.Class.forName(Class.java:344) ~[?:1.8.0_25]
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:?]
Java HotSpot(TM) 64-Bit Server VM warning: Using incremental CMS is deprecated and will likely be removed in a future release

Try adding more ram, if same thing, re-install java

did it crash when you run minecraft or it crash in-game?
it could be the launcher but that's just my guess and it could be the mod itself that caused it not to play.
these are just some things that could happen, I use Technic but sometimes i just copy and paste them to THE MINECRAFT LAUNCHER and test it
and see it if it works if it crashes Sometime's its could be the mod and it could be how many downloads. i use technic so that is a little different if your using a different mod pack downloader so it just could be the mod.
I don't code but these are just tip's i know from mod packs and what mod's dose it have (Do you know?)

Quote from ItsMrHexx»

Try adding more ram, if same thing, re-install java

Quote from ItsMrHexx»

Try adding more ram, if same thing, re-install java

Quote from gabuti»

java.lang.ClassNotFoundException

Quote from ChaosTheDude»

Not sure why everyone in this thread is suggesting things like "reinstall Java" or "use a different launcher"... that's not the problem.

You're using 1.7.10 mods with Forge 1.8 or some other version -- one that is not 1.7.10.

Quote from Skywing890»

Your right it says 1.8.0 so it means its 1.8 pack and someone used the incorrect forge for the mods Never thought of that
You must be right then
This is the best choice so far

at java.net.URLClassLoader$1.run(URLClassLoader.java:372) ~[?:1.8.0_25]

Already triying adding more ram, it didn't work. im reinstalling java 8 right now

Quote from gabuti»

Already triying adding more ram, it didn't work. im reinstalling java 8 right now

This is the only correct post in this thread, read it:

Quote from ChaosTheDude»

Not sure why everyone in this thread is suggesting things like "reinstall Java" or "use a different launcher"... that's not the problem.

You're using 1.7.10 mods with Forge 1.8 or some other version -- one that is not 1.7.10.

Also the forge version is 10.13.4, and that's the version for minecraft 1.7.10

(1.7.10-10.13.4.1448-1.7.10)

Quote from gabuti»

Also the forge version is 10.13.4, and that's the version for minecraft 1.7.10

(1.7.10-10.13.4.1448-1.7.10)

I changed the executable of java from the curse directory to the actual java directory on my machine, now this appears:

Error occurred during initialization of VM
Initial heap size set to a larger value than the maximum heap size
Java HotSpot(TM) Client VM warning: ignoring option PermSize=256m; support was removed in 8.0

just posted a pic

Quote from gabuti»

I changed the executable of java from the curse directory to the actual java directory on my machine, now this appears:

Error occurred during initialization of VM
Initial heap size set to a larger value than the maximum heap size
Java HotSpot(TM) Client VM warning: ignoring option PermSize=256m; support was removed in 8.0

Quote from sazrocks»

Full launcher log in a spoiler.

Done, forgot to hit your reply button.

I managed to fix this error. Downloaded forge 10.13.4.1448 and replaced the one that the modpack was using with it, renamed it and applying some changes to the modpack. thanks to everyone.