If you experience the error code R8102-101 on your Xbox 360, it typically indicates that your Netflix app is out of date. Follow the troubleshooting steps below to resolve the issue.
From the Xbox 360 Dashboard, go to Apps > My Apps.
Highlight the Netflix app.
Press the X button for app details.
Choose Delete > Yes.
From the Xbox 360 Dashboard, go to Apps.
Choose Netflix to download the app.
Try Netflix again.