I am using below script to create a folder:
$folder = $dList.AddItem("", [Microsoft.SharePoint.SPFileSystemObjectType]::Folder)
$folder["Title"] = "Test"
$folder.Update();
Error: Invalid item data - missing fileref
Try this PowerShell to get rid of missing FileRef issue:
$web = Get-SPWeb -Identity http://aissp2013/sites/Team
$dList = $web.Lists["Doc2"]
$folder = $dList.AddItem($dList.RootFolder.ServerRelativeUrl, [Microsoft.SharePoint.SPFileSystemObjectType]::Folder, "Folder2")
$folder["Title"] = "Test"
$folder.Update()
This will create a folder with Name "Folder2" and Title as "Test"