Sometimes the error occurs because the device is in Recovery Mode (Connect to iTunes screen) rather than DFU Mode (Black screen). DFU mode allows for a lower-level connection that bypasses some verification hurdles.
How to enter DFU Mode:
For devices with the A11 Bionic chip or newer, Apple introduced nonce entanglement. This means you cannot simply request SHSH without setting a specific generator (Boot Nonce). Solution: Use 3uTools’ "Set Boot Nonce" feature under Toolbox > Advanced before requesting SHSH. how to fix error unable to request shsh on 3utools when top
Your ISP’s default DNS may cache old responses from Apple or block the request entirely. Switching to a public DNS resolves most "Unable to request" errors. Sometimes the error occurs because the device is
Steps: