If you are trying to downgrade or upgrade your iOS device using 3uTools and are met with the error message "Unable to request SHSH" or subsequent installation failures, you are not alone. This is a common hurdle for users attempting to flash firmware outside of Apple's standard signing windows.
This guide explains why this error happens and provides step-by-step solutions to fix it. i unable to request shsh 3utools fix install
Ensure your computer has a stable internet connection. If you are on a restrictive network (like a school or office Wi-Fi), try switching to a mobile hotspot or a home network. How to Fix "Unable to Request SHSH" and
If you have used jailbreak tools (like Checkra1n, Unc0ver) or modified iTunes in the past, your computer's "Hosts" file might be redirecting SHSH requests to Cydia/Saurik's servers instead of Apple's. 3uTools needs to talk to Apple to get the blobs. Press Windows Key + R , type drivers , and hit Enter
How to fix it:
Windows Key + R, type drivers, and hit Enter.etc folder.hosts. Open it with Notepad (Run Notepad as Administrator).apple.com or gs.apple.com.# symbol at the beginning of the line to comment them out.
127.0.0.1 gs.apple.com to # 127.0.0.1 gs.apple.com.