How to upgrade Apple's mobile phone system to the previous version?

Materials/tools: Google browser, iTunes software.

1. First, please open the following address ipsw.me, click the iphone option on the page, and then return the iPhone to the old version of the system.

2. Open the option and enter the equipment that needs to be downgraded in the page. You can see the prompt message that you can downgrade to the old version of the system. A green tick √ indicates the system firmware that can be degraded, and a red X indicates the iPhone system that cannot be degraded.

3. After looking at the firmware of the system version that iPhone can be downgraded, we downloaded the firmware of the system version of iPhone through the iTools software toolbox.

4. According to the name and model of the personal iPhone device, select the corresponding system firmware version and download it to the computer.

5. After downloading the firmware, set it separately and save it in a folder, then connect the iPhone to the computer and open the Apple iTunes software.

6. When the iPhone switches to DUF mode, the problematic iPhone device will be displayed on iTunes software.

7. Then in iTunes software, press the keyboard Shift key+click Restore.

8. Open the downloaded firmware and you can recover.

9. Finally, slowly wait for the firmware recovery progress bar above the iTunes software to end, and then reactivate the iPhone.