Q: 4s stuck on slide to upgrade ios9

I'm having the same issue, though I'm upgrading from ios7.

When I plug my iPhone into my Mac Pro to try and reverse the issue with iTunes, iTunes provides the following pop-up message:

"To allow access, please respond on your iPhone..."

The message suggesting I should simply follow the prompt on my iPhone to 'slide to upgrade'. Of course, as per the OP's issue, my screen is unresponsive.

I can turn my iPhone off. When it comes on again I see the following screens:

[1] 'slide to upgrade': at this point the screen is responsive. When I slide my finger over the screen as per requested I'm greeted with my password screen. I am able to enter my password.

Then,

[2] The Apple logo appears with a loading bar underneath. The loading bar disappears and then I see the following:

[3] 'Hello' > 'slide to set up'

Again, the screen is responsive and I'm taken to another screen:

[4] Update Completed: your iPhone was updated successfully. There are just a few more steps to follow, and then you're done! <Continue>

I hit <Continue> and am taken to the 'slide to upgrade' screen, from which point the screen is no longer responsive.

Please advise.

I have gone through the loop that you are describing for hours tonight, using the tips from the support line,  and I finally got to the point where I could re-set up my phone and get my contacts, etc. back....all to have it go right back to the white screen "slide to upgrade" in the end.  Apple, please help us!

I've got my iPhone 4S working again and have successfully upgraded to ios 9.

My solution:

Effectively we need to completely wipe the phone and redownload ios 9. Hopefully you've backed up all your data...

Things you need:

iPhone switched off

A computer

Cable for connecting iPhone to your computer

With your computer on, connect your iPhone (still off) to your computer. As you insert the cable into the base of your iPhone 4S, hold down the HOME key on the face of the iPhone. Keep this depressed until you see an icon of what looks like a cable and iTunes logo. Then you can release the HOME key. Your iPhone is now in recovery mode.

Open iTunes. iTunes should now detect your iPhone. Select Restore iPhone.

This will result in all data on your phone being wiped and the new software reinstalled.

*Thank you to the Apple Care team who assisted me with this solution.

JD, I had to wipe off everything as well and install as a new device through iTunes. Is this the only solution that the Apple Care team gave you? Is there a way to restore your backup data without getting to the Slide to upgrade screen where it stucks?

same problem pls help

Use this Apple help article to fix your issue - If the Slide to Upgrade screen won't go away after you update to iOS 9 - Apple Support

I have the same problem with the slide to upgrade to iOS 9.

I've tried all of the suggested solutions and steps above but when I get to the restore the phone step it asks me to disable the Find My iPhone app on the phone before I can proceed with the restore.

How do I get past this as I can't get at the app?

HI, I'm currently traveling around New Zealand and this has happened with my iPhone 4s but the computer I used to back it up on is in the UK, so there is no chance of me being able to restore it from iTunes, what can I do?