i have an error message that says "the iPad could not be restored. an unknown error occurred (1100)

Hello and welcome to Apple Support Communities, GeoSchnell,

We understand you're seeing an error message when you attempt to restore your iPad. We'd be happy to provide information to help you address this.

If you've already followed the steps from the article you came from, you'll want to reach out to Apple Support for assistance: Contact Apple for support and service - Apple Support

Regards.