Recently my laptop was upgraded to Windows 10. Today while I was trying to access the SQL Server error log on my express instance (by executing xp_readerrorlog), I received the below error.
Msg 22004, Level 16, State 1, Line 0
Failed to open loopback connection. Please see event log for more information.
Msg 22004, Level 16, State 1, Line 0
Error log location not found.
When I expanded the SQL Server instance using SSMS, and expanded Management and select SQL Server Logs, no error log files were listed there. Although when I tried to open the SQL server error log using Notepad, I was able to read through the error log. Since the error was related to Loopback Connection, I suspect the issue might be related to network configuration.
Started looking at the SQL Server Configuration Manager, checked the Protocols used by the SQL Server instance. Both TCP/IP and Shared Memory was enabled. However, when I checked the SQL Native Client Configuration, I observed that the client protocol Shared Memory was in disabled state.
Once the Shared Memory client protocol is enabled, I was able to open the SQL Server logs using SSMS (both from GUI and using T-SQL query). Issue fixed.
Hope this may help someone. Happy Learning !!!