Minecraft Forums

I had major trouble downgrading to 1.2.5 using MCNostalgia. I kept getting the error that my MD5 of Minecraft did not match the current version or a vanilla version. I was unable to figure out how to get a "vanilla" version, whatever that is. So I switched to try MultiMC. I installed it and was able to create and run an instance of MC using it.

But now I'm stuck on how to install Forge using MultiMC. Do I need to install Forge specifically to that instance? That's what I tried to do, but now that instance won't run with the following error log, so maybe I missed something with how to properly install Forge using MultiMC. Any help would be MUCH appreciated as to how I should proceed. THANKS!

------------- MultiMC Crash Report -------------
Information:
	Date: 01-26-2013 08:54:34
	Operating System: Windows XP (build 2600, Service Pack 3)
	MultiMC Version: 4.3.0 jenkins-MultiMC4Windows-68
	Minecraft Version: 1.2.5

------------------ Mod Lists -------------------

----------------- Console Log ------------------
Instance folder is:
C:\Minecraft\MultiMC\instances\Doggy Talents\minecraft\

Instance started with command:
"C:\Program Files\Java\jre7\bin\java.exe" -Xms512m -Xmx1024m -jar MultiMCLauncher.jar "<username>" "<session ID>" "MultiMC: Doggy Talents" "854x480" "Mojang"

Loading jars...
Loading URL: file:/C:/Minecraft/MultiMC/instances/Doggy%20Talents/minecraft/bin/minecraft.jar
Loading URL: file:/C:/Minecraft/MultiMC/instances/Doggy%20Talents/minecraft/bin/lwjgl.jar
Loading URL: file:/C:/Minecraft/MultiMC/instances/Doggy%20Talents/minecraft/bin/lwjgl_util.jar
Loading URL: file:/C:/Minecraft/MultiMC/instances/Doggy%20Talents/minecraft/bin/jinput.jar
Loading natives...
java.lang.SecurityException: SHA1 digest error for net/minecraft/client/Minecraft.class
	at sun.security.util.ManifestEntryVerifier.verify(Unknown Source)
	at java.util.jar.JarVerifier.processEntry(Unknown Source)
	at java.util.jar.JarVerifier.update(Unknown Source)
	at java.util.jar.JarVerifier$VerifierStream.read(Unknown Source)
	at sun.misc.Resource.getBytes(Unknown Source)
	at java.net.URLClassLoader.defineClass(Unknown Source)
	at java.net.URLClassLoader.access$100(Unknown Source)
	at java.net.URLClassLoader$1.run(Unknown Source)
	at java.net.URLClassLoader$1.run(Unknown Source)
	at java.security.AccessController.doPrivileged(Native Method)
	at java.net.URLClassLoader.findClass(Unknown Source)
	at java.lang.ClassLoader.loadClass(Unknown Source)
	at java.lang.ClassLoader.loadClass(Unknown Source)
	at MultiMCLauncher.main(MultiMCLauncher.java:157)
Minecraft exited with code 4.
Minecraft has crashed!

Quote from Blazara

Wrong thread.

Which is the correct thread? Thanks.

Wrong Thread, (Belongs in support?)

Yeah but its just been released and I doubt his daughter is interested in bugtesting. Ummmm...I dont know anything about multimc but by reading the error report it looks like you should look in
C:\Minecraft\MultiMC\instances\Doggy Talents\minecraft\

for the minecraft.jar where you'd install the correct version of forge the old fashioned way.