Step 1: Prior to downgrade iOS with ReiBoot, you need to backup device data using iTunes.
Step 2: Then, ensure downgrade successfully, please turn off “Find My iPhone” on your device with the following instructions.
Step 3: After finishing the above steps, you can go back to ReiBoot UI to repair your iOS.
Note: The process won't erase your device data.
Step 4: After the repair is complete, your device will be downgrade to the latest iOS 14 official version, and now, you need to find the directory where your device was backed up previously. To do that:
For installing iTunes from the Microsoft Store:
You can locate the previous corresponding backup directory under your account name by: C:\Users\Administrator\Apple\MobileSync\Backup.
Note: Here, Administrator means Windows Administrator Name which is set by yourself. Different computers use different account names.
For not installing iTunes from the Microsoft Store:
You can locate this directory: %Appdata%\Apple Computer\MobileSync\Backup to find the previous corresponding backup.
Step 5: After locating the correct backup directory, scroll down to find the file “info.plist”.
Step 6: Open the file in Notepad, then use the shortcut “Ctrl + F” to run Find, then enter “Product Version” in the search box.
Step 7: When you locate where the “Product Version” is, modify the version number from 15.0 to 14.0, then save the file and close the window.
Step 8: Then re-open iTunes, the program will automatically detect the file you just backed up, click “Continue” to restore backup.
Step 9: After a few minutes, iTunes will pop up a message that your data has been restored to your device successfully.
Step 10: After operating the above steps, your device has been downgraded to the latest official version of iOS 14 without data loss.