Before fixing the problem, you need to understand its root cause. The phrase "when new" is the clue here. The error occurs for three primary reasons when a device or iOS version is brand new:
The "Unable to request SHSH" error in 3uTools typically occurs when the software cannot verify the digital signature (SHSH blob) required by Apple's servers to flash or restore a specific iOS version. Common Fixes how to fix error unable to request shsh on 3utools when new