I am trying to see what the trade-in value is of my old iPad, but it keeps telling me that the serial number is invalid. ??
iPad (4th gen) Wi-Fi
If you think there’s a typo, possibly, you can press and hold the number, too, to copy it for insertion: https://support.apple.com/en-us/HT204073
Another thought is if your iPad is an original iPad, it simply may no longer have any value for trade in.
If that is the case, then why doesn't Apple say so?
It would save us all a lot of bother
If you are entering the serial number on the back of the iPad or from going to Settings > General > About and you're being told the number is invalid, you should reach out to Apple Support.
You can use the Contact Support button at the top of this page
You can call Apple at: 1-800-MY-APPLE
You can go to your local Apple Store
I don't know if that's the case or not. It was a thought. After you posted yesterday a few more people also posted they were getting the same message about their serial number was not valid. It's also possible the Apple Trade In system was having technical difficulties yesterday.
To find out for sure though, reach out to Apple directly.
iPad Serial Number
