Upgrade Migration Error: Halting upgrade... Microsoft.SharePoint.SPException: User cannot be found.

This fixes 2 errors
Error 1) The migration upgrade error below[PortalSiteUpgradeAreaAndListingData] [12.0.1.0] [INFO]: Upgrade encountered an unexpected error.
Halting upgrade... Microsoft.SharePoint.SPException: User cannot be found. at Microsoft.SharePoint.SPUserCollection.GetByID(Int32 id) at Microsoft.SharePoint.SPSite.get_Owner() [SiteSequence] [ERROR]: User cannot be found.
Error 2) Manage Site Collection Owners User cannot be found

I've found a way to fix this but please try at your own risk and backup the database first! I think what is happening is that when SharePoint checks to see who the author (owner) of the site is, if the author doesn't exist Upgrade/migration fails.
The Owner of the site is stored in the Sites database table. The author of the site is stored in the Webs database table.

Step 1
Select * from Webs where FullUrl = ''
Here the full url is the one you are having problems with Copy the siteID it should look like this 3893DC55-756E-430C-8975-6214A531CAE1

Step 2
SELECT * FROM [FortBenn4_SITE].[dbo].[UserInfo] where tp_SiteId='3893DC59-756E-430C-8975-6214A531CAE1'
In here you get lots of records returned look for any valid user just copy the tp_ID for our example we make it 44

Step 3
The author and OwnerID bellow are the one you picked in step 2 (44) UPDATE [Sites] SET [OwnerID] = '44' WHERE [FullUrl]=’ '
Update Webs set Author='44' where FullUrl = ''
Step 4
Finally, go give ownership to the right user Go Windows SharePoint Services Manage Site Collection Owners Give the desired user ownership to the site
Let me know how it works make sure you test it on a backup environment