Resolving iOS9 "Slide to Upgrade" issue on iPad/iPhone

Please Note Apple's Official Fix now Available

Apple has pushed out an iOS update to address issues users have experienced with the Setup Assistant app getting stuck on “Slide to Upgrade.”  Please read Apple releases iOS 9.0.1 to fix Slide to Upgrade and other bugs

The following is left as an example of what persons had to do before to get the iPad/iPhone/iPod working. It is preferable to use the official Apple Fix above going forward. If it fails, try Method 2 below, it works. However use the the latest signed files from apple, the ones in green!!!

This the shortened version of the article "Solution to iOS9 "Slide to Upgrade" issue on iPad/iPhone"

Some Apple iPad/iPhone/iPod users updating to iOS9 have run into this "Slide to upgrade" issue. The issue at that step, is that it is simply not sliding. Here is one fix.

If you have tried Apple's solution or don't have a back up, skip Method 1 and try Method 2, the downgrade option. If you do a restore without a backup, you will wipe the phone and it will be just like new device.

Method 1 (Apple's solution)

If you don't have a backup I suggest you go to Method 2.

Source: https://support.apple.com/en-us/HT205239

Method 2 (Downgrade to 8.4.1 upgrade to 9.0.2 or latest)

1. Download iOS 8.4.1 OS  iOS 9.0.2 or latest from https://ipsw.me/
• Select your device  (look up model number  - model wiki )
  (Double check & ensure you pick the correct one - iPhone | iPad )
• Then iOS iOS 8.4.1 OS  iOS 9.0.2
• Download it (It is a large file, so be patient. It takes time. Note the location )
2. While that downloads, do steps 1 & 2 from Method 1 above. (repeated below for you as 3 & 4)
3. Open iTunes (preferably on a computer previously synced  with your device)
• Make sure iTunes is open first before connecting. n.b. - Ensure you have the latest version of iTunes! i.e. iTunes 12.3 at writing. To do this by clicking on the menu item 'help' in iTunes and then 'check for updates'. If you have to upgrade iTunes, please restart the PC/Mac after the updating.
• Then Connect your iOS device to the computer
• Do some diagnostics. Click on 'Help' then 
4. Select your device. If you don't see it listed, force restart your device by pressing and holding both the Sleep/Wake and Home button for at least 10 seconds, until you see the Apple logo. 
• You will need to enter you passcode 1/2 times 
• and "trust the computer" (if you have not already used the device with that machine)
5. When the download is complete,  
• Hold the Option / Alt Key on your Mac keyboard, OR Shift Key in Windows and 
• While holding the key, click on the "Check for Update or Update" button in iTunes,
• A file explorer window should now open. (n.b. Some guides suggest the restore iPhone/iPad option but that asks for you to disable "find my iPhone" plus if you don't have a backup it is useless and you lose your data. Don't use it). 
6. Browse to the file you downloaded , in step 1 above, select the file and click open
7. Watch the messages from extracting, to verify, to preparing until your phone comes back to life. (Please be patient as this can take up to 30 minutes)

That is it and there seems to be no loss of data which is good news.

Once done, backup your device before if you do anything else, then upgrade to iOS 9.0, if you have the heart for it!

The bug seems to affect devices upgrading from iOS7 to iOS9. 

Source: ios9news.net | IBTimes | Lewis Tech

Let me know if it helps. Feedback appreciated. Follow @roleli  message me and we can DM to chat if needed.

Updated September 21, 2015 
- Some people have reported losing contacts.
- Added restart instructions if updating iTunes
- Added link to forced restart link for more information
Updated September 22, 2015
- Added note - Take note on renaming the ipsw file extension to .ipsw if saved as a .zip
Update September 23, 2015
- Add a bold warning to avoid clicking Restore. Use the Update option
- Apple releases Official Fix. Added to Page
Update September 25, 2015
- Adjusted the order in Step 3 under Method 2. Open iTunes first, once open then connect device
Update October 3, 2015
- iOS 8.4.1 is no longer signed. Use the latest, the ones in green