Thicket “_files” folder and SharePoint 2007 (MOSS)

I got into this one when I was asked to put some Microsoft Publisher generated files into SharePoint 2007 site. Basically I got “index.html” file and “index_files” folder with some images and html files inside. I did put the index file into the root, then created the Document Library named “index_files”. Also I uploaded all the files into it without any problems using “Open in Windows Explorer” functionality. Everything actually started to work well. Then I was surprised that I don’t see this document library in SharePoint Designer. When I opened it from the browser – it was empty. But it was still showing all the files when opened with Windows Explorer. When I tried to change document library settings to work with content types, the whole settings page started to throw error.

I did some research and it looks like SharePoint 2007 has some native support of so called “thicket” folder (“_files” folder). SharePoint does not allow creating such a folder when you don’t have a corresponding (parent) file. When you try to create such folder using SharePoint Designer, it appends its name with an underscore at the end. SharePoint web interface hides content of such folder, while keeping those files accessible from Windows Explorer or when you browse/refer it directly.

My advise – try to avoid thickets in SharePoint. Those are hard to manage there.