I moved to a new server and all went well.  Then did an upgrade that had numerous errors because I didn't know you had to unzip all of the folders within folders.  So I tried to undo the upgrade with my backup copies and that failed, then ended up just deleting all files and website and starting over. But I keep getting this error message even though all of the files are from weeks before I tried the move to a new server and the separate sql database was restored to a copy from weeks ago. Any help is greatly appreciated.  I run IIS7.5 with .net 4.5 and a separate sql server database.

Collection cannot be null.
Parameter name: c

Description:An unhandled exception occurred during the execution of the current web request. Please review the stack trace for more information about the error and where it originated in the code.

Exception Details:System.ArgumentNullException: Collection cannot be null.
Parameter name: c

Source Error:

[ArgumentNullException: Collection cannot be null.
Parameter name: c]
   System.Collections.ArrayList..ctor(ICollection c) +10647211
   DotNetNuke.Entities.Portals.PortalController.GetPortals() +180
   DotNetNuke.Common.Initialize.CacheMappedDirectory() +36
   DotNetNuke.Common.Initialize.InitializeApp(HttpApplication app, Boolean& initialized) +324
   DotNetNuke.Common.Initialize.Init(HttpApplication app) +191
   DotNetNuke.HttpModules.RequestFilter.RequestFilterModule.FilterRequest(Object sender, EventArgs e) +229
   System.Web.SyncEventExecutionStep.System.Web.HttpApplication.IExecutionStep.Execute() +136
   System.Web.HttpApplication.ExecuteStep(IExecutionStep step, Boolean& completedSynchronously) +69