Myself and a couple of others have posted the following as an add-on to another thread.  I imagine that is why we haven't gotten any replies....  so I am reposting as a new post in hopes that someone will notice/help  :)

The following occurs on the Module Definitions page after an upgrade from 4.9 to 5.1.

Error: Module Definitions is currently unavailable.
DotNetNuke.Services.Exceptions.ModuleLoadException: d:\hosting\hptes\sdportal\Admin\ModuleDefinitions\ModuleDefinitions.ascx.vb(61): error BC30311: Value of type 'String' cannot be converted to 'System.Version'. ---> System.Web.HttpCompileException: d:\hosting\hptes\sdportal\Admin\ModuleDefinitions\ModuleDefinitions.ascx.vb(61): error BC30311: Value of type 'String' cannot be converted to 'System.Version'. at System.Web.Compilation.BuildManager.CompileWebFile(VirtualPath virtualPath) at System.Web.Compilation.BuildManager.GetVPathBuildResultInternal(VirtualPath virtualPath, Boolean noBuild, Boolean allowCrossApp, Boolean allowBuildInPrecompile) at System.Web.Compilation.BuildManager.GetVPathBuildResultWithNoAssert(HttpContext context, VirtualPath virtualPath, Boolean noBuild, Boolean allowCrossApp, Boolean allowBuildInPrecompile) at System.Web.Compilation.BuildManager.GetVPathBuildResultWithAssert(HttpContext context, VirtualPath virtualPath, Boolean noBuild, Boolean allowCrossApp, Boolean allowBuildInPrecompile) at System.Web.Compilation.BuildManager.GetVPathBuildResult(HttpContext context, VirtualPath virtualPath, Boolean noBuild, Boolean allowCrossApp, Boolean allowBuildInPrecompile) at System.Web.UI.TemplateControl.LoadControl(VirtualPath virtualPath) at System.Web.UI.TemplateControl.LoadControl(String virtualPath) at DotNetNuke.UI.ControlUtilities.LoadControl[T](TemplateControl containerControl, String ControlSrc) at DotNetNuke.UI.Modules.ModuleHost.LoadModuleControl() --- End of inner exception stack trace ---

And this on the Skins page.

Error: Skins is currently unavailable.
DotNetNuke.Services.Exceptions.ModuleLoadException: d:\hosting\hptes\sdportal\Admin\Skins\EditSkins.ascx.vb(175): error BC30456: 'GetSkin' is not a member of 'DotNetNuke.UI.Skins.SkinController'. ---> System.Web.HttpCompileException: d:\hosting\hptes\sdportal\Admin\Skins\EditSkins.ascx.vb(175): error BC30456: 'GetSkin' is not a member of 'DotNetNuke.UI.Skins.SkinController'. at System.Web.Compilation.BuildManager.CompileWebFile(VirtualPath virtualPath) at System.Web.Compilation.BuildManager.GetVPathBuildResultInternal(VirtualPath virtualPath, Boolean noBuild, Boolean allowCrossApp, Boolean allowBuildInPrecompile) at System.Web.Compilation.BuildManager.GetVPathBuildResultWithNoAssert(HttpContext context, VirtualPath virtualPath, Boolean noBuild, Boolean allowCrossApp, Boolean allowBuildInPrecompile) at System.Web.Compilation.BuildManager.GetVPathBuildResultWithAssert(HttpContext context, VirtualPath virtualPath, Boolean noBuild, Boolean allowCrossApp, Boolean allowBuildInPrecompile) at System.Web.Compilation.BuildManager.GetVPathBuildResult(HttpContext context, VirtualPath virtualPath, Boolean noBuild, Boolean allowCrossApp, Boolean allowBuildInPrecompile) at System.Web.UI.TemplateControl.LoadControl(VirtualPath virtualPath) at System.Web.UI.TemplateControl.LoadControl(String virtualPath) at DotNetNuke.UI.ControlUtilities.LoadControl[T](TemplateControl containerControl, String ControlSrc) at DotNetNuke.UI.Modules.ModuleHost.LoadModuleControl() --- End of inner exception stack trace ---

Any insight is much appreciated.

If you check in the \Providers\DataProviders\SqlDataProvider\05.00.00.log file do you see something similar to the following:

System.Data.SqlClient.SqlException: Violation of UNIQUE KEY constraint 'IX_DesktopModules_ModuleName'. Cannot insert duplicate key in object 'dbo.DesktopModules'.
The statement has been terminated.
   at System.Data.SqlClient.SqlConnection.OnError(SqlException exception, Boolean breakConnection)
   at System.Data.SqlClient.SqlInternalConnection.OnError(SqlException exception, Boolean breakConnection)
   at System.Data.SqlClient.TdsParser.ThrowExceptionAndWarning(TdsParserStateObject stateObj)
   at System.Data.SqlClient.TdsParser.Run(RunBehavior runBehavior, SqlCommand cmdHandler, SqlDataReader dataStream, BulkCopySimpleResultSet bulkCopyHandler, TdsParserStateObject stateObj)
   at System.Data.SqlClient.SqlCommand.RunExecuteNonQueryTds(String methodName, Boolean async)
   at System.Data.SqlClient.SqlCommand.InternalExecuteNonQuery(DbAsyncResult result, String methodName, Boolean sendToPipe)
   at System.Data.SqlClient.SqlCommand.ExecuteNonQuery()
   at DotNetNuke.Data.SqlDataProvider.ExecuteADOScript(String SQL)
   at DotNetNuke.Data.SqlDataProvider.ExecuteScript(String Script, Boolean UseTransactions)

If so, please log that you encountered this issue to the following Gemini ticket so that it can be addressed as a bug: http://support.dotnetnuke.com/issue/ViewIssue.aspx?ID=10526&PROJID=23

Can someone tell me what the *CntrlSrc* field in the [ModuleControl] table is for the ModuleDefinitions module after upgrading to 5.1.1?

Mine shows Admin/ModuleDefinitions/ModuleDefinitions.ascx. 

I have read that this is no longer used, but curious as to what it should be.