Under the hood, these document sets are nothing more than the old fashioned folders on steroids. This becomes clear when you change the content type for a folder. If you have enabled the document sets site feature, and added the document set content type to your library, you can change folders into document sets. This is especially useful in migration scenario's, if you were already using folders for the same purposes you now would like to use document sets for.
However, the result of this content type switch is not the same as when you create a new document set. Some properties do not update correctly. The resulting document set does not get its landing page and it doesn't get the pretty icon. The culprit is the ProgId property, which should be set to 'SharePoint.DocumentSet'. This property is used by SharePoint to launch the correct program when you open a document (such as a Word or Excel document).
You can go one of two ways in fixing an issue like this. You can create an event receiver which sets the property correctly when the change is made. This is the approach used in a project on codeplex, SharePoint 2010 Folder To Document Set Conversion Fix, by Robert R. Freeman. The main advantage of this solution is that it will fix the document set the moment you update it. A drawback is that you need to deploy custom code, which isn't always an option. Also, folders that have had their content type updated in the past are not fixed
A second solution is to just script it, and fix the document sets that are not functioning correctly in one go. For this you can use the script below.
Of course, all the regular legal stuff applies. Use at your own risk. I do not accept any liability for what happens when you run this script. And never, never, run a random script you've downloaded from the internet against a production environment without properly testing and examining it.
param( [string]$WebUrl = $(throw "WebUrl required."), [string]$ListName = $(throw "ListName required."), [bool]$disableEventFiring = $false ) #Region [ Load Assemblies ] $spNotFoundMsg = "SharePoint not found. Run this script from a SharePoint server that is part of the farm where you want to update your content types" if ([Reflection.Assembly]::LoadWithPartialName("Microsoft.SharePoint") -eq $null) { throw $spNotFoundMsg; } if ([Reflection.Assembly]::LoadWithPartialName("Microsoft.Office.Server") -eq $null) { throw $spNotFoundMsg; } if ([Reflection.Assembly]::LoadWithPartialName("System.Xml.Linq") -eq $null) { throw $spNotFoundMsg; } if ([Reflection.Assembly]::LoadWithPartialName("Microsoft.Office.Server") -eq $null) { throw $spNotFoundMsg; } if ([Reflection.Assembly]::LoadWithPartialName("Microsoft.Office.Server.UserProfiles") -eq $null) { throw $spNotFoundMsg; } if ([Reflection.Assembly]::LoadWithPartialName("Microsoft.SharePoint.Taxonomy") -eq $null) { throw $spNotFoundMsg; } $snapin = Get-PSSnapin | Where-Object {$_.Name -eq 'Microsoft.SharePoint.Powershell'} if ($snapin -eq $null) { Write-Output "Loading Microsoft SharePoint Powershell Snapin" Add-PSSnapin "Microsoft.SharePoint.Powershell" } #endregion Start-SPAssignment -Global $web = Get-SPWeb $WebUrl -EA 1 $list = $web.Lists[$ListName] if ($list -eq $null) { throw "List '$ListName' not found at '$WebUrl'" } Write-Host "Found list '$ListName' at '$WebUrl'" -ForeGroundColor Green if($disableEventFiring) { Write-Host "Disabling event firing" -ForeGroundColor Yellow $myAss = [Reflection.Assembly]::LoadWithPartialName("Microsoft.SharePoint"); $type = $myAss.GetType("Microsoft.SharePoint.SPEventManager"); $prop = $type.GetProperty([string]"EventFiringDisabled",[System.Reflection.BindingFlags] ([System.Reflection.BindingFlags]::NonPublic -bor [System.Reflection.BindingFlags]::Static)); $prop.SetValue($null, $true, $null); } $count = 0 $folderCollection = $list.Folders foreach($folder in $folderCollection) { if ($folder.ContentType.Id.ToString().StartsWith("0x0120D520")) { if($folder.ProgId -ne "SharePoint.DocumentSet") { Write-Host "Found a document set to fix:" $folder.Title -ForeGroundColor Yellow $folder.ProgId = "SharePoint.DocumentSet" $folder.Update() $documentSet = [Microsoft.Office.DocumentManagement.DocumentSets.DocumentSet]::GetDocumentSet($folder.Folder) $documentSet.Provision() Write-Host "Document set" $folder.Title "is fixed" -ForeGroundColor Green $count++ } } } if ($count -eq 0) { Write-Host "Found no document sets requiring an update!" -ForeGroundColor Yellow } else { Write-Host "Updated $count document sets!" -ForeGroundColor Green } Stop-SPAssignment -Global <# .SYNOPSIS Fix document sets in a SharePoint library .DESCRIPTION When manually updating the content type of a folder to a document set, not all properties are propertly updated by SharePoint. This script fixes these broken document sets. This script can be run more than once. .PARAMETER WebUrl Specifies the url the web hosting the document sets to fix .PARAMETER ListName Specifies the display name of the library holding the document sets to fix .PARAMETER disableEventFiring Optional parameter. Set to $True to prevent the update from firing events for event receivers. Can be useful in custom code scenario's .INPUTS None. You cannot pipe objects to DocumentSetFixer.ps1. .OUTPUTS None. DocumentSetFixer.ps1 does not generate any output. .EXAMPLE C:\PS> .\DocumentSetFixer.ps1 -WebUrl "http://mysitecollection/myweb" -ListName "Shared Documents" Fix all documents sets in the library "Shared Documents" on the SharePoint web at "http://mysitecollection/myweb". .EXAMPLE C:\PS> .\DocumentSetFixer.ps1 -WebUrl "http://mysitecollection/myweb" -ListName "Shared Documents" -disableEventFiring $true Fix all documents sets in the library "Shared Documents" on the SharePoint web at "http://mysitecollection/myweb". This fix will not trigger event receivers on the document sets. .LINK Developed by: http://www.vxcompany.com #>