Xbox 360 error code 0x8000FFFF is an error that usually occurs after you sign in to Xbox Live on Xbox 360. It could mean that some features are not available due to temporary system maintenance, an unexpected Xbox Live issue, or a network configuration issue.
1. Check Xbox Live server
"Xbox 360 error code 0x8000FFFF" appears when you have trouble connecting to Xbox Live Core Service. It could be caused by the server itself. The server might have an issue or under maintenance which leads to the error. To confirm, visit this link here to check the Xbox Live Core Service status. If the status is not normal, wait for it to recover.
2. Check Internet connection
If Xbox Live Core Service is normal “Xbox 360 error code 0x8000FFFF” could be caused by your internet connection. Your network setting may be the problem, or network firewall might be blocking your access to Xbox Live Core Service server or an issue occur with your internet service provider (ISP). Test your network, to determine the problem causing the error.
- Do an internet speed test, see speedtest.net. If your internet connection speed is not normal, call the internet service provider (ISP).
- If it is fine, turn off your modem router for at least three minutes. Check if it solves the problem.
- If the connection is WiFi, make sure your Xbox 360 is receiving enough WiFi signal.
- If the connection is ethernet cable, reconnect the cable or try other LAN ports.
- If the issue still exists, a router might have a firewall. Connect your Xbox 360 to your modem, if it fixes the issue.