Stratagerm

Cool, thanks. I forgot or didn't know that the Minecraft launcher could change the Game Directory after the fact, and handles moving the files. This is why the Forge installer can be so simple, because the Minecraft launcher can move it after installation. The issue isn't for me, but what's simplest for my players, who are young relatives not local to me. For the record, on a system that's been running Minecraft 1.8 the sequence to do a 1.7.10 Forge installation into a separate directory is: [*]Run Minecraft launcher [*]Check for a profile called Forge. If it exists, rename it to something else [*]Create a profile for stock 1.7.10, if one doesn't already exist, using the default Game Directory [*]Start 1.7.10, quit immediately (this step may be redundant but causes no harm) [*]Download & install Forge for 1.7.10 [*]Edit the new "Forge" profile, change both the profile name and the Game Directory [*]Start the renamed profile, quit immediately so the Game Directory change takes effect For someone with several keybinds, you can copy in your 1.8 options.txt to the new game directory, keeping in mind that if you set the 1.8 render distance > 16 it needs to be changed in options immediately after launching 1.7.10 before a world is loaded. Again, thanks much! [Edit: No files are copied or moved by either the Minecraft launcher or Forge. What happens is that if the specified directory doesn't exist, a new one is created. See also the post below from Lex Manos.]

I have done that, before the Forge install. Are you saying to do it after installing Forge? This is the relevant paragraph:

Hi all, I'm getting back into modded Minecraft after some time away. I'm in the early stages of setting up a private modpack for a handful of unsophisticated users. None of the mods I plan to use are on 1.8 yet, so 1.7.10 is the best option. I installed Forge for 1.7.10 without issue, fired it up, and Minecraft immediately crashed due to a render distance issue. When using the standard Minecraft Launcher to create a new profile for 1.7.10, by default it uses the same directory as the current version of Minecraft, which results in the same options.txt file being used by both versions. 1.8 supports high render distance values in the options.txt file which will cause 1.7.10 to crash with a horribly obscure crash dump. This bug has been reported to Mojang as Render Distance glitch when falling back to older version of minecraft. Since I don't want my players to have to have to fiddle with render distance or deal with this crash, I thought I'd have them set up a launcher profile with the Game Directory changed to a subdirectory of .minecraft running version 1.7.10. This creates a new options.txt file in that subdirectory which is not shared with 1.8 and thus avoids the issue. For stock Minecraft it works fine. What doesn't work fine is installing Forge into this subdirectory because forge-1.7.10-10.13.4.1490-1.7.10-installer.jar expects to find launcher_profiles.json in the specified directory. It wouldn't install until I copied launcher_profiles.json into the directory (and the new profile is created in this copy, which means a symlink is needed in order for the new profile to show up when the launcher runs). I don't want my players to have to copy or symlink launcher_profiles.json, so it seems that installs using the launcher's profile feature won't work correctly due to the simple nature of the Forge installer which expects to find launcher_profiles.json in its target directory. (To work correctly with launcher profiles, the Forge installer needs the user to specify two paths: the install directory and the location of launcher_profiles.json. This way it could open the launcher_profiles.json file in the specified directory, populate a dropdown with the profiles, and then install into the Game Directory for the selected profile grab the Minecraft assets from the selected profile. A simple installer becomes less simple.) My conclusion is that the best way to keep things simple for my players to avoid sharing the options.txt file (and others) between a current Minecraft 1,8 install and a Forge 1.7 install is to have them set up a duplicate Minecraft install, say to a directory ".minecraft_1_7_10_mods" and tell them not to run 1.8 using this install. This will slightly incovenience the players by requiring them to use a different icon to start Minecraft when using the modpack, but it seems best overall. Thoughts, anyone? Have I missed something? A workaround for the Forge installer perhaps? Thanks. [Edited to correct the changes needed to the Forge launcher.]