If there is a problem during the upgrade process of a SQL Instance, then follow these instruction,
Check the archive Summary.txt, which is located at C:\Program Files\Microsoft SQL Server\XXX\Setup Bootstrap\Log directory
The second file that keeps logging important information about the error message is the StatusInfromation.xml and is located in the C:\Program Files\Microsoft SQL Server\XXX\Setup Bootstrap\Log\ YYYYMMDD_HHMMSS\MSSQLSERVER\Datastore directory
| SQL Version | Folder Number |
| SQL Server 2017 | 140 |
| SQL Server 2016 | 130 |
| SQL Server 2014 | 120 |
| SQL Server 2012 | 110 |
| SQL Server 2008, SQL Server 2008 R2 | 100 |
| SQL Server 2005 | 90 |