I'm looking to downgrade my iOS 10 to iOS 9

[DeltaMac]

Maybe you can run the old app after jailbreaking your iPhone?
The jailbreak will NOT provide a method to revert to an older iOS version that is no longer signed, but maybe that is not required if the app will work from a JB device. Might be worth the effort for that.

But, absolutely, there is no way to revert to an older, no-longer-signed iOS. iOS 9 is no longer signed...
Cannot be done, even after you apply the "BS" rule

Looks like a quick trip to wasteland now, but though I would point out that reverting to older iOS versions is completely at Apple's end, and has everything to do with what Apple will allow. That's all there is. Your opinion about downgrading to an older iOS is, unfortunately, just a fantasy.

 

[Apple Master]

When I do it, I will happily come back and show you the results.

 

[DeltaMac]

That's easy to say, but you will find it can't be done.

But, also no harm in reporting that you have failed.
That will be your result, but I imagine that you won't be so happy with that.

 

[Paddle1]

To be clear, the iPhone 5 and 5c are the last iPhones that are publicly downgradable with a jailbreak. Apple improved security with the 5S and at this time newer phones cannot be downgraded unless Apple is signing the version you want to install.

 

[Apple Master]

That's easy to say, but you will find it can't be done.

But, also no harm in reporting that you have failed.
That will be your result, but I imagine that you won't be so happy with that.

It can be done. You naysayers will eat your words I guarantee.

 

[Weaselboy]

Moderator Note:

The OP's question has been answered and we are not accomplishing anything here. Thread closed.