Thankfully, the 20% error that was causing us problems earlier today has been solved. If you received this error, you need to downgrade your version of iTunes.
The simple fix is to downgrade to iTunes 12.1.0, and just like that, it will work. If you’re having problems with TaiG 2.0.0 hanging at 20% completion for the iOS 8.3 jailbreak, then try downgrading your version of iTunes.
Keep in mind that you will have to uninstall any previous versions of iTunes before installing an older version.
You can find older versions of iTunes using a simple Google search. You can use IPSW.me for iTunes downgrades.