If I create a template from a 6.0 site, I can use that to build a second 6.0 site without issue (I have not exhaustively pushed the envelope on this, but on a simple site, it does appear to work).

If I try to use a template created from a 5.X->6.0 upgraded site (the sites were all built with 5.X but are currently running on 6.0 without issue), I get the following failure when building a new site based on that template:

Error parsing Portal TemplateViolation of UNIQUE KEY constraint 'IX_ModulePermission'. Cannot insert duplicate key in object 'dbo.ModulePermission'. The statement has been terminated. at System.Data.SqlClient.SqlConnection. (SqlException exception, Boolean breakConnection) at System.Data.SqlClient.SqlInternalConnection. (SqlException exception, Boolean breakConnection) at System.Data.SqlClient.TdsParser.ThrowExceptionAndWarning() at System.Data.SqlClient.TdsParser.Run(RunBehavior runBehavior, SqlCommand cmdHandler, SqlDataReader dataStream, BulkCopySimpleResultSet bulkCopyHandler, TdsParserStateObject stateObj) at System.Data.SqlClient.SqlDataReader.ConsumeMetaData() at System.Data.SqlClient.SqlDataReader.get_MetaData() at System.Data.SqlClient.SqlCommand.FinishExecuteReader(SqlDataReader ds, RunBehavior runBehavior, String resetOptionsString) at System.Data.SqlClient.SqlCommand.RunExecuteReaderTds(CommandBehavior cmdBehavior, RunBehavior runBehavior, Boolean returnStream, Boolean async) at System.Data.SqlClient.SqlCommand.RunExecuteReader(CommandBehavior cmdBehavior, RunBehavior runBehavior, Boolean returnStream, String method, DbAsyncResult result) at System.Data.SqlClient.SqlCommand.RunExecuteReader(CommandBehavior cmdBehavior, RunBehavior runBehavior, Boolean returnStream, String method) at System.Data.SqlClient.SqlCommand.ExecuteScalar() at Microsoft.ApplicationBlocks.Data.SqlHelper.ExecuteScalar(SqlConnection connection, CommandType commandType, String commandText, SqlParameter[] commandParameters) at Microsoft.ApplicationBlocks.Data.SqlHelper.ExecuteScalar(String connectionString, CommandType commandType, String commandText, SqlParameter[] commandParameters) at Microsoft.ApplicationBlocks.Data.SqlHelper.ExecuteScalar(String connectionString, String spName, Object[] parameterValues) at DotNetNuke.Data.SqlDataProvider.AddModulePermission(Int32 moduleID, Int32 PermissionID, Int32 roleID, Boolean AllowAccess, Int32 UserID, Int32 createdByUserID) at DotNetNuke.Security.Permissions.PermissionProvider.SaveModulePermissions(ModuleInfo objModule) at DotNetNuke.Security.Permissions.ModulePermissionController.SaveModulePermissions(ModuleInfo objModule) at DotNetNuke.Entities.Modules.ModuleController.DeserializeModule(XmlNode nodeModule, XmlNode nodePane, Int32 portalId, Int32 tabId, PortalTemplateModuleAction mergeTabs, Hashtable hModules) at DotNetNuke.Entities.Tabs.TabController.DeserializePanes(XmlNode nodePanes, Int32 PortalId, Int32 TabId, PortalTemplateModuleAction mergeTabs, Hashtable hModules) at DotNetNuke.Entities.Tabs.TabController.DeserializeTab(XmlNode nodeTab, TabInfo objTab, Hashtable hTabs, Int32 PortalId, Boolean IsAdminTemplate, PortalTemplateModuleAction mergeTabs, Hashtable hModules) at DotNetNuke.Entities.Portals.PortalController.ParseTab(XmlNode nodeTab, Int32 PortalId, Boolean IsAdminTemplate, PortalTemplateModuleAction mergeTabs, Hashtable& hModules, Hashtable& hTabs, Boolean IsNewPortal) at DotNetNuke.Entities.Portals.PortalController.ParseTabs(XmlNode nodeTabs, Int32 PortalId, Boolean IsAdminTemplate, PortalTemplateModuleAction mergeTabs, Boolean IsNewPortal) at DotNetNuke.Entities.Portals.PortalController.ParseTemplate(Int32 PortalId, String TemplatePath, String TemplateFile, Int32 AdministratorId, PortalTemplateModuleAction mergeTabs, Boolean IsNewPortal) at DotNetNuke.Entities.Portals.PortalController.CreatePortal(String PortalName, UserInfo objAdminUser, String Description, String KeyWords, String TemplatePath, String TemplateFile, String HomeDirectory, String PortalAlias, String ServerPath, String ChildPath, Boolean IsChildPortal)

I have about a dozen websites of varying complexity on an old server, which as I mentioned has been upgraded to 6.0
My hope was to export these as templates one at a time, move the template over to a new server with a new clean 6.0 install, and bring them back to life on the new server.  When done, I'll shut down my old server.

Chris,

As I mentioned in my post, that's exactly what I did.  I had a 5.X DNN installation which I upgraded to 6.0
Now if I export any of those working websites as templates, copy to templates to another 6.0 server (brand new install), that's when I experience the failure.

Cheers,
Tim

I updated my old server with the 6.1 update.  This fixed the inability to edit HTML, and also seems to have fixed the export/import issue.  I suspect they are related.