An exception of type Microsoft.SharePoint.Upgrade.SPUpgradeException was thrown. Additional exception information:
Action 126.96.36.199 of Microsoft.SharePoint.Upgrade.SPConfigurationDatabaseSequence2 failed.Microsoft.SharePoint.Upgrade.SPUpgradeException:
Action 188.8.131.52 of Microsoft.SharePoint.Upgrade.SPConfigurationDatabaseSequence2 failed. --->
The id 0a54b6fc-79ad-4412-b51d-3091dd622976 is in
use. An Microsoft.SharePoint.Administration.SPServer named "sql" is using the same id as the new object named "sql" of type Microsoft.SharePoint.Administration.SPServer. Every object must contain a unique id. Either update the new object's id or delete the existing object and try again.
The solution that worked for me is to empty out the "Dependencies" and "Objects" table in the WSS Config database and run the wizard again.