Apple only "signs" specific iOS versions (usually the latest ones). If you are trying to install an older version that Apple has stopped signing, the SHSH request will fail because the servers won't provide the necessary digital signature.
The for why you can’t request SHSH and how to fix it: i unable to request shsh 3utools fix install
DNS issues can prevent the request from going through. Apple only "signs" specific iOS versions (usually the
Are you encountering the frustrating error message "Unable to request SHSH" while trying to use 3uTools to jailbreak or restore your iOS device? You're not alone. Many users have reported this issue, which can be caused by a variety of factors, including outdated software, incorrect configuration, or corrupted files. In this article, we'll walk you through the possible causes of the error and provide a step-by-step guide on how to fix and install 3uTools. Are you encountering the frustrating error message "Unable