System errors
Error codes and messages from Windows itself: access denied, missing files, failed services and similar system errors.
- Xbox app and Microsoft Store error 0x80070520: how to fix it0x80070520 ends in 0x520, which Windows lists as "a specified logon session does not exist". It shows up on Windows 10 and 11 in the Xbox app or the Microsoft Store when the account session is missing or invalid. Signing out and back in, then repairing or resetting the Store and Xbox apps, is the usual route to a fix.
- Windows 11 error logs: where to find them and how to read themWindows 11 keeps errors in several places: the event logs, the update and DISM logs, and crash dump files. Start with Event Viewer (System and Application), filter by Error level around the time of the problem, and use PowerShell for a faster or deeper look.
- Remote Desktop error 0x204: "We couldn't connect to the remote PC"Error 0x204 is not a documented Microsoft code. The Remote Desktop and Windows App clients show it when a connection fails at "Initiating Remote Connection". Treat it as a general "can't reach the remote PC" problem and check the host, the name or IP, port 3389 and the Remote Desktop settings, in that order.
- Windows Defender Firewall error 0x800706d9: how to fix itError 0x800706d9 is a generic RPC error ("There are no more endpoints available from the endpoint mapper"). It usually means the Windows Defender Firewall service is stopped or disabled. Setting that service to Automatic and starting it is the first thing to try. Microsoft's own page covers only that service, and only on Windows Server 2008, so the Windows 10 and 11 steps rest on community reports.