A momentary drop in connection during the verification process.
In 3uTools, click in the bottom right corner. 3utools Error Unable To Request Shsh
Look at the list of available firmwares. If the version you want does not have a green "Signed" status (or if it's explicitly marked as unsigned), you cannot flash it unless you have previously saved SHSH blobs for that specific device. 2. Update 3uTools and iTunes Compatibility issues can trigger server errors. A momentary drop in connection during the verification