Hello,
performing the upgrade all the messages said 'success' except for the last 3 which were:

00:00:17.875 - Installing Package File jQueryMigrate: Error!
00:00:18.188 - Installing Package File jQueryUI: Error!
00:00:18.235 - Installing Package File KnockoutMapping: Error!

The corresponding error in the event log is of the kind:

Package Installation aborted - jQuery-UI:Cannot insert duplicate key row in object 'dbo.PackageDependencies' with unique index 'IX_PackageDependencies_Dependant'. The duplicate key value is (114, jQuery, 1.6.4). The statement has been terminated.

The site itself looks fine, but it continuously logs exceptions such as:

System.ArgumentException: An item with the same key has already been added.
at System.ThrowHelper.ThrowArgumentException(ExceptionResource resource)
at System.Collections.Generic.Dictionary`2.Insert(TKey key, TValue value, Boolean add)
at DotNetNuke.Entities.Portals.PortalController.GetPortalSettingsDictionaryCallback(CacheItemArgs cacheItemArgs)

What's the cause and how can I fix it, please?

Thanks
Franco

Well, I think I was able to fix it by following this thread http://www.dnnsoftware.com/forums/for...

In particular here is the query (be CAREFUL to select the portals you need in case of multiple sites):

delete x from (
select *, rn=row_number() over (partition by settingname order by settingname)
from portalsettings
) x
where rn > 1;

So far so good...
Franco