I've recently changed to the new Minecraft launcher, and I have noticed a change in the .minecraft folder layout. I can no longer install mods just by copying it over into the versions/1.6.1 jar file, as this file refreshes every time it is launched.

For those who don't know what I am talking about, here is the new layout:

New minecraft folder layout.

I am specifically trying to install Optifine, which does work with 1.6.1. Where do I drag in the mod files now? I can't seem to find a jar file that is suited to it, except in the version folder, but as I stated above, this refreshes every time.

After copying a recent version and renaming it in the version folder, I get this error in the development console:

Unexpected exception refreshing version list
java.lang.IllegalArgumentException: Version '1.6.1' is already tracked
    at net.minecraft.launcher.updater.VersionList.addVersion(VersionList.java:91)
    at net.minecraft.launcher.updater.LocalVersionList.refreshVersions(LocalVersionList.java:44)
    at net.minecraft.launcher.updater.VersionManager.refreshVersions(VersionManager.java:47)
    at net.minecraft.launcher.Launcher$2.run(Launcher.java:164)
    at java.util.concurrent.Executors$RunnableAdapter.call(Unknown Source)
    at java.util.concurrent.FutureTask$Sync.innerRun(Unknown Source)
    at java.util.concurrent.FutureTask.run(Unknown Source)
    at java.util.concurrent.ThreadPoolExecutor.runWorker(Unknown Source)
    at java.util.concurrent.ThreadPoolExecutor$Worker.run(Unknown Source)
    at java.lang.Thread.run(Unknown Source)
  • 3
    Where is this version of Optifine coming from? I went looking for the official install instructions, but I only see versions for 1.5.2 available on the official Optifine site. Commented Jun 30, 2013 at 8:37
  • Regardless, this error is showing up with no mods aswell. I search optifine 1.6.1 and I believe it was minecraftdl.
    – Brandyn
    Commented Jun 30, 2013 at 10:04
  • 1
    MinecraftDL is an illicit mod redistribution site with no content oversight. It's not a trustworthy download source. Commented Jun 30, 2013 at 20:15
  • But anyway, if you're getting that error without any mods then mods aren't relevant to the question, and it should be rewritten to clearly describe the situation in which the error occurs. Commented Jun 30, 2013 at 20:17
  • 1
    Try to find the folder 'Versions' click 1.6.1 and find the Jar file :) or try to add a 'Profile' new function for Modded Clients :)
    – user51068
    Commented Jul 1, 2013 at 13:07

4 Answers 4


There doesn't seem to be any official way. Then again, modding the game by splaying open and modifying the internals of the .jar file was never really officially supported, either. The new launcher is, ultimately, part of a rather large series of changes to Minecraft, including making mods actually something the game supports via the new Resource Pack stuff, but until that time, modding is a bit more awkward.

However, there's still a way to do it. Go into the versions folder inside .minecraft, and copy the version you want to mod. Rename the copied folder, and both the files inside, to some new name, say "modded 1.blah". Lastly, open the .json file in a text editor, and change the line that will read something like "id": "1.6.1", so that the ID matches the new name. The new launcher should now show a version "modded 1.blah" in the list, but since that version doesn't exist on the Minecraft servers, it won't get overwritten. Splay open and tinker with the .jar file in there the same way you always would with the old launcher.

If you are using the new launcher with an older version of Minecraft, then the mods you are using may attempt to access files in the bin folder directly. If this is the case, you can simply create a folder named 'bin' in the .minecraft folder where they are looking for it, and add the files the mod needs in there. The mod should find the files, and carry on as it used to, not knowing the difference.

  • I'm not getting anything in the local versions list. I have renamed everything, as you instructed to a random name, even the .json file. Usually I can figure these things out, but not this time. Is there an official link or something to this?
    – Brandyn
    Commented Jun 30, 2013 at 8:17
  • @ReallyGoodPie, I had forgotten the step about changing the ID inside the .json file. Answer has been updated, sorry about that. Commented Jun 30, 2013 at 15:53
  • Cheers, managed to figure it out before reading this again. Thankyou :)
    – Brandyn
    Commented Jul 1, 2013 at 13:10
  • @Billy Mailman - I can't find the version in the Minecraft launcher. I went into edit profile and checked under the versions and it wasnt there. I have edited everything both in the .json file and I added a replica folder in the versions folder with the same name
    – user51096
    Commented Jul 1, 2013 at 22:24
  • 1
    I just did the exact steps in my answer, and once I went in to Edit Profile, a "Release CUSTOM" option appeared in the list. Make sure you've got the latest launcher, and try again, maybe? Commented Jul 2, 2013 at 0:04

Seeing as none of the answers so far have covered this, it is now possible to do it. For a long while now, APIs such as Forge have transitioned to the new layout for quite some time now, and Forge especially has its own installer that you can use to automatically drop a modified .jar archive already prepared to be used.

The universal-OS installer (used since 1.6 Forge) looks something like this.

Mod system installer: options to set installation directory and to install client or server API or to simply extract it are also included.


If you're willing to download MagicLauncher in addition to your regular launcher, it supports the original <1.6 way of installing mods. Just copy the mod files into the .jar, and MagicLauncher won't overwrite it. You now only need the official launcher to get new releases.


There is a way. Go to your .minecraft folder, go into versions and click 1.6.1 then add a .zip file extension to 1.6.1.jar to make it 1.6.1.jar.zip. Double click it, then drag the mod files into the folder called 1.6.1.jar.

  • This has already been established to not work; the 1.6.1.jar file is updated every time. So any mods installed are removed on launch. See the above method.
    – Unionhawk
    Commented Jul 2, 2013 at 1:48
  • This is downvoted beacsuse it is 1.6.1. This is 1.8 Commented Nov 12, 2014 at 0:22
  • 2
    @TheIdiotGamer your comment is incorrect. at the time of posting for this question, the accepted answer and this answer 1.8 did not exist.
    – Memor-X
    Commented Nov 25, 2014 at 2:54

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