Document Set Site-collection restore to non-root site collection errors File not found

So I was helping a friend of mine where he reported a problem about the restore:

He moved the site collection from a top level site collection (http://test-moss:6001) to a path based site ( using powershell Restore-SPSite command. After the restore we are experience ‘File not found’ error although we can see all files using Sharepoint Designer and also don’t get error message in
the log.  

following thread also talk about similar issues, where I posted the answer as well but thought I will blog it in case if someone needs it:


Check in the ULS log when you try to browse to the newly restored site collection, check if there is anything in ULS (enable verbose logging). 2.
Open the site in SPD and open the _cts under All Files, open the Document set content type folder and then open the docsethomepage.aspx page (should be inside it). Now open this page in Advanced edit mode and check if you have any such tags “/_controltemplates/” strings with “~/_controltemplates “ (Note: the difference “~” difference. So for e.g.:

                             <%@ Register TagPrefix="wssuc"TagName="LinksTable" src="" %>

Should now look like      <%@ Register TagPrefix="wssuc" TagName="LinksTable" src="~/_controltemplates/LinksTable.ascx" %>

You should fine multiple such controltemplate entries replace all of them wth “~” before it and then save that page


3. Once you have done that go to the site content types gallery and select the “Document Set” content type and go to its setting and then check the “Update the Welcome Page of Document Sets inheriting from this content type” checkbox  and make sure to check the yes option for the Update all content types inheriting from this type. 

Hopefully this should get you back in shape on the site collection, other thing you can check is the Master Page for that site collection as well.