Hi MDEzzat,
Welcome to the Apple Support Communities!
We are happy to help with the issue you are having the error you are seeing. Can you tell us where exactly you are seeing the error and what you were trying to do before you saw it? Does the same thing happen if you try opening a different app on your iPad?
If you are using a specific app, you can force quit, restart your device and try again.
You want make sure you are running the latest version of software. Learn how to Update your iPhone, iPad, or iPod touch here.
If you still see the error, it could be a connectivity issue. You should test your iPad with a different WiFi network and see what happens. Also take a look at If your iPhone, iPad, or iPod touch won’t connect to a Wi-Fi network.
Cheers!