I also have this problem, please give me a solution. thanks

If your are experiencing difficulties with (re)activation of your iPad, you may have more success if you connect your iPad to a PC (with iTunes installed) or a Mac (with iTunes or Finder - as appropriate for the installed version of macOS). Once connected to your computer, your iPad will be detected - and you should be able to activate using iTunes.

1. Make sure that you have the latest version of macOS or the latest version of iTunes.
2. Check that your computer has an Internet connection.
3. With the cable that came with your iPad, connect your iPad to your computer. Locate your device on your computer.
4. Wait while your computer detects and activates your iPad:

• If you see an alert that shows "Set up as New" or "Restore from Backup", it means your iPad is activated.
• If you get an error message that says the "activation information was invalid" or "activation information could not be obtained from the device", use recovery mode to restore your iPhone.

A restart of your WiFi Router and/or a change of DNS settings may be helpful.

To restart you home router, disconnect power - then wait at least 30 seconds before restarting. When you router has rebooted (which may take several minutes), force-restart your iPad:

• On an iPad with a Home button: Press and hold the top button and the Home button at the same time. When the Apple logo appears, release both buttons.
• On an iPad with Face ID: Press and quickly release the volume up button, press and quickly release the volume down button, then press and hold the top button. When the Apple logo appears, release the button.

For recommended DNS servers (configured at your home router and/or your iPad), you might choose one of the following Recursive DNS Providers (IPv4 and IPv6 addresses included below):

Quad9

9.9.9.9

149.112.112.112

2620:fe::fe

2620:fe::9

OpenDNS

208.67.222.222

208.67.220.220

2620:0:ccc::2

2620:0:ccd::2

Cloudflare+APNIC

1.1.1.1

1.0.0.1

2606:4700:4700::1111

2606:4700:4700::1001

Should it be necessary to escalate your issue to Apple Support, the quickest route to engaging with Apple Support will be via the  Get Support link at top-right of this page.

You clearly have an iPad2, iPad3 or iPad mini1 WiFi Only - for which the final compatible version of iOS os iOS 9.3.5.

Update to a more recent version of iOS is not possible.

Apple ended update support for these models in September 2016. Your iPad cannot be updated to iOS 10 or later major versions of iOS, as the internal hardware does not meet the minimum technical requirements for new versions of iOS/iPadOS. This limitation cannot be bypassed; these are 32-bit architecture devices, whilst all recent versions of iOS/iPadOS are designed for 64-bit hardware platforms. iPad2, iPad3 and iPad mini1 are obsolete.