Hi, I've downloaded the modpack using Twitch (I've played it before on this computer, but had hard drive issues and had to reinstall Twitch) but the game won't start, giving me the following message:

Failed to download file, the file contents differ from what was expected.
Name: jna-4.4.0.jar
URL: https://libraries.minecraft.net/net/java/dev/jna/jna/4.4.0/jna-4.4.0.jar
Filename on disk: jna-4.4.0.jar
Path: C:\Users\aider\Twitch\Minecraft\Install\libraries\net\java\dev\jna\jna\4.4.0\jna-4.4.0.jar
Exists: File

I've tried to play on the three most recent versions (1.2.26, 1.2.25, 1.2.24) and have had the same problem. Not sure what the message is trying to say.

I ended up finding the solution by searching. I simply had to enter the URL the message gave me into my browser, download the file and replace the existing version at the provided path with the downloaded one. Not a problem with the modpack, it was on my end.