I'm trying to play on my friends server with a 1.15 modpack but every time I launch it it crashes Instantly I've tried to repair it but still hasnt worked. I've also tested modpacks from 1.15.2 to 1.12.2 and only 1.12.2 worked
The errors I got were
Couldn't fetch SHA1 checksum for https://s3.amazonaws.com/Minecraft.Download/versions/1.15.2/1.15.2.jar
Have local file C:\Program Files (x86)\Minecraft Launcher\Install\versions\1.15.2\1.15.2.jar but don't know what size or hash it should be. Have to assume it's good.
Failed to find Minecraft resource version 1.15.2-20200515.085601 at C:\Program Files (x86)\Minecraft Launcher\Install\libraries\net\minecraftforge\forge\1.15.2-31.2.8\forge-1.15.2-31.2.8-client.jar
Process crashed with exit code 1