Office 365 - Upload and Set a Master Page

We all know that Custom Master Pages for SharePoint Online are not recommended, right?

I had a customer that decided they needed to use a custom Master Page and asked for my assistance to automate the process of uploading and configuring their custom Master Page, never one to shy away from writing a script I put the following together, which does the following:

  • Uploads a Master Page ($MasterPage) to the SharePoint Online Site ($Site) specified in the variables.
  • Checks Out and then Checks In this Master Page (to create a major version that can be used).
  • Configures both the MasterURL and CustomMasterURL properties for the Site to use the newly uploaded Master Page

All you need to do is update the highlighted variables. You could quite easily wrap this in a ForEach loop to apply the Master Page to multiple SharePoint Online sites.

#Add references to SharePoint client assemblies and authenticate to Office 365 site
Add-Type -Path "C:\Program Files\Common Files\Microsoft Shared\Web Server Extensions\16\ISAPI\Microsoft.SharePoint.Client.dll"
Add-Type -Path "C:\Program Files\Common Files\Microsoft Shared\Web Server Extensions\16\ISAPI\Microsoft.SharePoint.Client.Runtime.dll"
$Username = ""
$Site = ""
$MasterPage = "D:\MasterPages\MasterPage.master"
$Password = Read-Host -Prompt "Please enter your password" -AsSecureString
$Context = New-Object Microsoft.SharePoint.Client.ClientContext($Site)
$Creds = New-Object Microsoft.SharePoint.Client.SharePointOnlineCredentials($Username,$Password)
$Context.Credentials = $Creds

#Bind to the Master Page Gallery
$List = $Context.Web.Lists.GetByTitle("Master Page Gallery")

#Upload the Master Page specified in the $MasterPage variable
$FileStream = New-Object IO.FileStream($MasterPage,[System.IO.FileMode]::Open)
$FileCreationInfo = New-Object Microsoft.SharePoint.Client.FileCreationInformation
$FileCreationInfo.Overwrite = $true
$FileCreationInfo.ContentStream = $FileStream
$FileCreationInfo.URL = $MasterPage.Split("\")[-1]
$Upload = $List.RootFolder.Files.Add($FileCreationInfo)
$Web = $Context.Web

#Check the Master Page Out and then In to create a major version
$Item = $List.RootFolder.Files.GetByUrl(($Web.ServerRelativeUrl) + "/_catalogs/masterpage/" + ($MasterPage.Split("\")[-1]))
$CheckOut = $Item.CheckOut()
$CheckIn = $Item.CheckIn("Upload",[Microsoft.SharePoint.Client.CheckinType]::MajorCheckIn)

#Set the Master Page
$Web = $Context.Web
$MasterURL = $Context.Web.ServerRelativeUrl + "/_catalogs/masterpage/" + $MasterPage.Split("\")[-1]
$WebMaster = $Web.MasterUrl = $MasterURL
$CustomMaster = $Web.CustomMasterUrl = $MasterURL

Brendan Griffin - @brendankarl