Every thing works great in DNN6.2.9 - When I upgrade to DNN7.1.2  I get an exception when I access either the Admin->Files or Host->Files tabs.

During the upgrade I see:
00:00:03.865 -   Converting old Folders to new format. Total: 680 [Remaining: 680]
00:00:03.885 -   Converting old Folders to new format. Total: 680 [Remaining: 180]
00:00:03.899 -   Conversion of old Folders Completed. Total Converted: 680
Success

I suspect that 180 folders aren't correct, even though the script returned success.

What changes were made to folders in DNN7?  How do you recommend I troubleshoot the problem?

When I access either Admin->Files or Host->Files I get an exception

Sebastian    Here is the exception --------- Dave Snow

AssemblyVersion:7.1.2

PortalID:0

PortalName:Aging Safely, Inc.

UserID:4

UserName:WebMaster

ActiveTabID:5973

ActiveTabName:File Management

RawURL:/asi3/DesktopModules/DigitalAssets/API/ContentService/GetFolderContent

AbsoluteURL:/asi3/desktopmodules/digitalassets/api/contentservice/getfoldercontent.aspx

AbsoluteURLReferrer:http://localhost/asi3/Host/FileManagement/tabid/5973/portalid/0/Default.aspx

UserAgent:Mozilla/5.0 (Windows NT 6.1; WOW64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/45.0.2454.101 Safari/537.36

DefaultDataProvider:DotNetNuke.Data.SqlDataProvider, DotNetNuke

ExceptionGUID:98251a24-7c89-45f5-93e7-179850602efb

InnerException:Unhandled Error:

FileName:

FileLineNumber:0

FileColumnNumber:0

Method:System.Web.Http.WebHost.HttpControllerHandler.EndProcessRequest

StackTrace:

Message:

System.Exception: Unhandled Error:  ---> System.ArgumentException: Item has already been added. Key in dictionary: 'UserInfo'  Key being added: 'UserInfo'
   at System.Web.Http.WebHost.HttpControllerHandler.EndProcessRequest(IAsyncResult result)
   at System.Web.HttpApplication.CallHandlerExecutionStep.OnAsyncHandlerCompletion(IAsyncResult ar)
   --- End of inner exception stack trace ---

Source:

Server Name: DavidWSnow-PC