PowerShell To Replace The Old Content Type With New One

One of our users came up with a request to exchange all the old content types with the new one.

If you Google it you will find lots of resources which can help you achieve it.

But our user had a special request while changing the content type, the modified by or modified time should not be changed.

Below is the PowerShell to achieve it.

Add - PSSnapin Microsoft.SharePoint.PowerShell# Custom PowerShell Function to
switch Content type of all items stored in a SharePoint library
Function Change - ItemContentType {
    param(
        [Microsoft.SharePoint.SPWeb] $Web = $(
            throw "Web URL!"), [string] $ListName = $(
            throw "ListName"), [string] $OldContentTypeName = $(
            throw "OldContentTypeName"), [string] $NewContentTypeName = $(
            throw " 'NewContentTypeName"))# Get the list
    $List = $Web.Lists[$ListName]# Get the new content type
    $NewContentType = $List.ContentTypes[$NewContentTypeName]# Iterate through each item in the list
    foreach($item in $list.Items) {
        if ($item.ContentType.Name - eq $OldContentTypeName) {#
            Change the content type
            $item["ContentTypeId"] = $NewContentType.Id
            $item.SystemUpdate()
            Write - host "Content type changed for item: "
            $item.id
        }
    }
}#Variables
for processing
$WebURL = "Site URL"
$ListName = "Library Name"
$ContentTypeName = "New Content type Name"#Get the Web and List
$Web = Get - SPWeb $WebURL
$List = $Web.lists.TryGetList($ListName)
if ($list - ne $null) {#Call the
    function to add content type
    Change - ItemContentType $web $list "Old Content type Name"
    "New Content type Name"
}

Happy SharePointing.