After building out a new farm and applying the various SharePoint updates, you received the following error after installing the Infrastructure Updates and running the Config wizard:
“An exception of type Microsoft.SharePoint.PostSetupConfiguration.PostSetupConfigurationTaskException was thrown. Additional exception information: Failed to upgrade SharePoint Products and Technologies.”
The reason this happens is because the farm doesn’t have any Web Apps provisioned so the Web.config file which is supposed to be in the 12\template\Layouts folder is missing.
To resolve this, simply copy the Web.config file in the 12\Config folder and paste it into your 12\templates\Layouts. Now run the Config wizard again and everything should work smoothly.