After installing SP2010 SP1 and trying to run psconfigui (UI version of the Configuration Wizard) you end up with error:
[psconfigui] [SPUpgradeSession] [INFO] [11/8/2011 3:29:14 PM]: No context object
[psconfigui] [SPUpgradeSession] [ERROR] [11/8/2011 3:29:14 PM]: This upgrade session has been stopped. Possible causes include the process being terminated abruptly or the OS has rebooted. Please restart the upgrade again.
The only sensible error you see in PSCDiagnostics log is:
The exclusive inplace upgrader timer job failed.
Followed by generic error:
Failed to upgrade SharePoint Products.
You retry the Configuration Wizard, and you end up with same error.
Run psconfig.exe (command line version) from command line and don’t use the graphical UI version.
Command to use: psconfig -cmd upgrade -inplace b2b -wait