Also read: Top 10 Must Have Cydia Tweaks for iPhone, iPad, iPod touch How-to Fix An Unknown Error (1600) while restoring iPhone custom firmware iOS 4.2.1. The iPhone “iPhone” could not be restored. An unknown error occurred (1600). Fix 1600 Unknown Error by following these steps: Download iReb latest version Run iReb iReb will kill … Continue reading How-to Fix An unknown error (1600)