: Apple stops "signing" older iOS versions shortly after new releases. You cannot restore or downgrade to an unsigned version because Apple's servers will refuse the SHSH request.
If you are an iPhone, iPad, or iPod touch user who enjoys tinkering with firmware, you have likely heard of . This all-in-one management tool for Windows is a favorite among repair technicians and enthusiasts because it allows flashing, jailbreaking, and backing up data with ease. how to fix error unable to request shsh on 3utools when upd
: Apple stops "signing" older iOS versions shortly after new releases. If you are trying to install a version that Apple has closed, 3uTools cannot retrieve the required SHSH blobs from Apple's servers. You can verify which versions are still signed on sites like Check Network and USB Connections : Apple stops "signing" older iOS versions shortly