Modpack help

Hey guys, i'm trying to make a modpack for my friends on Curse and its crashing.

I don't know enough to fix it so any help would be great.

here's the error log:

13:47:44.613
Preparing to launch minecraft client for forge-14.23.5.2854
13:47:44.618
Prepared asset index
13:47:44.629
Have 1346 total files to check or download
13:47:44.632
Waiting for 1346 futures
13:47:45.042
Couldn't fetch SHA1 checksum for https://s3.amazonaws.com/Minecraft.Download/versions/1.12.2/1.12.2.jar
13:47:45.043
Have local file C:\Users\Dylan\Documents\Curse\Minecraft\Install\versions\1.12.2\1.12.2.jar but don't know what size or hash it should be. Have to assume it's good.
13:47:49.355
Checking installations.
13:47:49.355
Minecraft client forge-14.23.5.2854 is ready to start.
13:47:49.355
Starting!
13:47:49.355
Nothing to download!
13:47:49.355
Extracting 3 files!
13:47:49.553
Using default game log configuration client-1.12.xml (outputs XML)
13:47:49.553
Installing versions!
13:47:50.151
Loading tweak class name net.minecraftforge.fml.common.launcher.FMLTweaker
13:47:50.226
Using primary tweak class name net.minecraftforge.fml.common.launcher.FMLTweaker
13:47:50.226
Calling tweak class net.minecraftforge.fml.common.launcher.FMLTweaker
13:47:50.243
Forge Mod Loader version 14.23.5.2854 for Minecraft 1.12.2 loading