I had a few errors in upgrading from 4.9.3 to 5.1.2.  Here is a partial list of messages:

Upgrading DotNetNuke
Current Assembly Version: 05.01.02
Current Database Version: 04.09.03


Upgrade Status Report
00:00:00.031 - Upgrading to Version: 05.01.02
00:00:00.249 -   Executing Script: 05.00.00.SqlDataProvider Error! (see 05.00.00.log for more information)
00:00:28.828 -   Executing Script: 05.00.01.SqlDataProvider Success
00:00:36.731 -   Executing Script: 05.01.00.SqlDataProvider Error! (see 05.01.00.log for more information)
00:00:52.941 -   Executing Script: 05.01.01.SqlDataProvider Success
00:01:00.593 -   Executing Script: 05.01.02.SqlDataProvider Success
00:01:06.762 -   Executing Application Upgrades: 05.00.00 Error!
00:03:35.331 -   Executing Application Upgrades: 05.00.01 Success
00:03:35.363 -   Executing Application Upgrades: 05.01.00 Success
00:03:54.484 -   Executing Application Upgrades: 05.01.01 Success
00:03:54.688 -   Executing Application Upgrades: 05.01.02 Success

So ...

Where are the log files?  I haven't found them.

Where can I find more about the Application Upgrades error.

The site seems to be working just fine.  But, I have noticed that the list of modules on the Extensions page does not include any of the installed modules, other than the admin and host modules.  However, it is possible to add installed modules to a page, even though they don't appear on the Extensions page.