Just a day ago, I was installing SQL Server Express on backup computer. I only use this computer when I have something to experiment. While installing SQL Server Express I found following error in my error log which prevented successful installation to computer. It was difficult to initially understand the problem by itself, after some try and error I found the solution.
Error: 15372, Severity: 16, State: 1.
Failed to generate a ser instance od SQL Server due to a failure in starting the process for the user instance. The connection will be closed.
Solution for this error is fairly simple.
Delete the directory “c:\Documents and Settings\username\Local Settings\Application Data\Microsoft\Microsoft SQL Server Data\SQLEXPRESS “
Delete the directory “c:\Users\<username>\AppData\Local\Microsoft\Microsoft Sql Server Data\SQLEXPRESS”
Reboot the system.
Watch SQL in Sixty Seconds video to Resolve Connection Error:
Reference : Pinal Dave (http://blog.sqlauthority.com)