If you are seeing the "updated" version of this error, it typically means your software tool (like iTunes, Finder, or a third-party flashing utility) is looking for a specific component of the firmware that doesn't match your device's hardware revision.
This means the software cannot find the "iBSS" or "iBEC" files—the "loaders" that tell the iPhone how to boot into a state where it can accept new software. Common Causes for the "Loader Not Found" Error
This is the specific hardware board configuration (CPID) for that device.
Right-click and select -> Search automatically . 5. Try a Different Port and Cable
The "loader for iphone9,3d101ap not found updated" error is almost always a . By manually downloading the correct GSM-specific IPSW and using the most recent version of your flashing tool in DFU mode, you can usually bypass the missing loader requirement.
Release the button but keep holding Volume Down for another 5 seconds.