After upgrading Sitecore from version 8.2.7 to 10.3.1 I encountered an unexpected complication when trying to import a Template into my Project’s Solution; the Feature, Foundation and Project folders would show up as “Duplicate” from the Get Sitecore Items TDS menu, making it impossible to grab new content:

Clearing the TDS cache, cleaning the Visual Studio solution and removing existing imported Items from the project and trying to re-add them yielded no result.

This is when I noticed that the Sitecore environment did have those Items visible in the Content Editor, and attempting to remove them was met with the following error message:

“Some of selected items are in resources and cannot be deleted.”

This is because since version 10.1, Sitecore introduced Items-as-Resources that are not stored in the SQL Server database but as .dat files and as such cannot be deleted. Those Folders have static IDs that is different from that of the Items we inherited from our 8.2.7 instance and thus figured as duplicate.

The Solution in our case was copying all Children from the original Foundation, Feature and Project folders to the static version of those folders and then delete the originals.

The Get Sitecore Items functionality resumed working immediately after this change.