Launcher Opens and Closes after pressing play on custom modpack.

[Spyblox007]

I've been trying to set up a modpack so my friends can play on a server I'm also trying to set up, and I have followed the directions I have read online. This includes copying the mods and config folder from a client that has only used those mods before and creating a bin folder with the latest 1.12.2 forge inside, then zipping them all up and sending them to technic through dropbox. Installing the modpack using the launcher works fine, but when I press play the launcher will close and open back up again. I'm new to this and don't really know what I am doing, but from looking at the console it looks like to me that the problem begins at the line "Exception in thread "main" [20:26:09] [main/INFO] [STDERR]: [java.lang.Throwable$WrappedPrintStream:println:-1]: java.lang.NoClassDefFoundError: net/minecraftforge/fml/relauncher/IFMLLoadingPlugin", which after Googling makes me think I made some type of stupid mistake, but all the mods and the forge should be 1.12.2, and they all worked when I launched it on the Minecraft Launcher and on MultiMC (I did use this originally for making the modpack, but I ended up switching over to the regular Minecraft Launcher so I could get a clean version of the config). 

Here is a pastebin of the full console, any help or advice would be greatly appreciated!:

https://pastebin.com/A2WWecmM

[JaariAtmc]

8 hours ago, Spyblox007 said:

I've been trying to set up a modpack so my friends can play on a server I'm also trying to set up, and I have followed the directions I have read online. This includes copying the mods and config folder from a client that has only used those mods before and creating a bin folder with the latest 1.12.2 forge inside, then zipping them all up and sending them to technic through dropbox. Installing the modpack using the launcher works fine, but when I press play the launcher will close and open back up again. I'm new to this and don't really know what I am doing, but from looking at the console it looks like to me that the problem begins at the line "Exception in thread "main" [20:26:09] [main/INFO] [STDERR]: [java.lang.Throwable$WrappedPrintStream:println:-1]: java.lang.NoClassDefFoundError: net/minecraftforge/fml/relauncher/IFMLLoadingPlugin", which after Googling makes me think I made some type of stupid mistake, but all the mods and the forge should be 1.12.2, and they all worked when I launched it on the Minecraft Launcher and on MultiMC (I did use this originally for making the modpack, but I ended up switching over to the regular Minecraft Launcher so I could get a clean version of the config). 

Here is a pastebin of the full console, any help or advice would be greatly appreciated!:

https://pastebin.com/A2WWecmM

Forge is for 1.7.10.

[Lord Ptolemy]

Moved to platform Pagoda.