SharePoint Online: Add Attachment to List Item using PowerShell

Requirement: Add Attachment to SharePoint Online List Item.

SharePoint Online: How to Add Attachment to List Item?

Attachments are a great way to keep related documents and files together with your list items in SharePoint Online. In this post, we’ll walk you through the process of adding an attachment to a SharePoint Online list item.

To add an attachment to a list item in SharePoint Online, follow these steps:

  1. Navigate to the SharePoint Online list >> Select the List Item you want to add attachments
  2. Edit List Item >> Scroll down and Click on “Add Attachments” link in the Edit pane.
    sharepoint online add attachment to list item powershell
  3. This opens the browse dialog window., Select attachments to add.
  4. Click on Save to complete adding an attachment to the list item.
SharePoint Online list item attachment size limit: The file size limit on SharePoint Online list attachments is 250 MB!

PowerShell to Add an Attachment to List Item:

PowerShell can make the process easy if you want to automate the process of attaching files to a list. Let’s walk you through how to attach a file to a specific list item in your SharePoint Online list using PowerShell. This is a handy way to attach multiple files to list items without opening the item editor.

Here is the PowerShell script to add attachments to the list item:

#Load SharePoint CSOM Assemblies
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"

Function Add-AttachmentToListItem()
        [Parameter(Mandatory=$true)] [string] $SiteURL,
        [Parameter(Mandatory=$true)] [string] $ListName,
        [Parameter(Mandatory=$true)] [string] $ItemID,
        [Parameter(Mandatory=$false)] [string] $AttachmentPath
    Try {
        #Setup Credentials to connect
        $Cred = Get-Credential
        $Cred = New-Object Microsoft.SharePoint.Client.SharePointOnlineCredentials($Cred.UserName,$Cred.Password)
        #Setup the context
        $Ctx = New-Object Microsoft.SharePoint.Client.ClientContext($SiteURL)
        $Ctx.Credentials = $Cred

        #Get the List & List Item
        $List = $Ctx.Web.Lists.GetByTitle($ListName)
        $ListItem = $List.GetItemByID($ItemID)

        #Get All existing attachments
        $AttachmentFiles = $ListItem.AttachmentFiles

        #Check if attachment file name exists already
        $FileName = Split-Path $AttachmentPath -Leaf
        $AttachmentFile = $AttachmentFiles | where { ($_.FileName -eq $FileName) }
        If($AttachmentFile -eq $Null)
            #Get the Attachment file from local disk
            [Byte[]]$Bytes = [System.IO.File]::ReadAllBytes($AttachmentPath)
            $ContentStream = New-Object -TypeName System.IO.MemoryStream -ArgumentList @(,$Bytes)
            #Create Attachment object
            $AttachmentCreation = New-Object Microsoft.SharePoint.Client.AttachmentCreationInformation
            $AttachmentCreation.ContentStream = $ContentStream
            $AttachmentCreation.FileName = $FileName

            write-host  -f Green "Attachment Added to List Item!" 
            write-host -f Yellow "Attachment File Name Exists already!"
    Catch {
        write-host -f Red "Error Adding Attachment to List!" $_.Exception.Message

#Set Parameters
$SiteURL= ""

#Call the function to copy list items
Add-AttachmentToListItem -SiteURL $SiteURL -ListName $ListName -ItemID $ItemID -AttachmentPath $AttachmentPath

PnP PowerShell to Add Attachment to List Item

Let’s add an attachment to the SharePoint Online list item with PnP PowerShell.

#Set Variables
$SiteURL = ""
$ListName = "Projects"
$ItemID ="2"
$FilePath ="C:\Docs\UserInfo.csv"

#Connect to PnP Online
Connect-PnPOnline -Url $SiteURL -Interactive

#Get the List Item
$Item  = Get-PnPListItem -List $ListName -Id $ItemID

#Get the File and Add to List Item Attachment
$FileStream = New-Object IO.FileStream($FilePath,[System.IO.FileMode]::Open) 
$AttachmentInfo = New-Object -TypeName Microsoft.SharePoint.Client.AttachmentCreationInformation 
$AttachmentInfo.FileName =  Split-Path $FilePath -Leaf 
$AttachmentInfo.ContentStream = $FileStream
$AttchedFile = $Item.AttachmentFiles.Add($AttachmentInfo) 

How about adding multiple attachments to the list item? Let’s add all files from a given folder to SharePoint Online.

#Set Variables
$SiteURL = ""
$ListName = "Projects"
$ItemID ="2"
$FolderPath = "C:\Temp\Docs"

#Connect to PnP Online
Connect-PnPOnline -Url $SiteURL -Interactive

#Get the List Item
$ListItem  = Get-PnPListItem -List $ListName -Id $ItemID

#Function to Add all files as a attachment to list item
Function Add-AttachmentsFromFolder($ListItem, $FolderPath)
    #Get All existing attachments from list item
    $AttachmentFiles = Get-PnPProperty -ClientObject $ListItem -Property "AttachmentFiles"

    #Get the File and Add to List Item Attachment
    ForEach ($File in  (Get-ChildItem $FolderPath -File))
        $AttachmentFile = $AttachmentFiles | Where { ($_.FileName -eq $File.Name) }
        If($AttachmentFile -eq $Null)
            $AttachmentInfo = New-Object -TypeName Microsoft.SharePoint.Client.AttachmentCreationInformation 
            $AttachmentInfo.FileName =  $File.Name
            $AttachmentInfo.ContentStream = $File.OpenRead()
            $AttchedFile = $ListItem.AttachmentFiles.Add($AttachmentInfo) 
            Write-host -f Green "Added Attachment File:"$File.FullName
            write-host -f Yellow "Attachment '$($File.Name)' Exists already!"
#Call the function to add all attachments from folder
Add-AttachmentsFromFolder $ListItem $FolderPath

You can also attach a file to a List Item in SharePoint Online using the PnP PowerShell cmdlet: Add-PnPListItemAttachment

$SiteURL = ""
$ListName = "Projects"
$ListItemID = 13
$AttachmentFile = "C:\Temp\MonthlyRpt.csv"

#Connect to SharePoint Online Site
Connect-PnPOnline -Url $SiteURL -Interactive

#Attach file to list item
Add-PnPListItemAttachment -List $ListName -Identity $ListItemID -Path $AttachmentFile

My other post on downloading attachments from SharePoint Online list: How to Download Attachments from SharePoint Online List using PowerShell?

Salaudeen Rajack

Salaudeen Rajack - Information Technology Expert with Two-decades of hands-on experience, specializing in SharePoint, PowerShell, Microsoft 365, and related products. He has held various positions including SharePoint Architect, Administrator, Developer and consultant, has helped many organizations to implement and optimize SharePoint solutions. Known for his deep technical expertise, He's passionate about sharing the knowledge and insights to help others, through the real-world articles!

4 thoughts on “SharePoint Online: Add Attachment to List Item using PowerShell

  • I have not been able to add any files with the third script, error:

    Cannot convert the argument “parameters”, with the value:
    “Microsoft.SharePoint.Client.AttachmentCreationInformation”, for “Add”, to type
    “Microsoft.SharePoint.Client.AttachmentCreationInformation”: “Cannot convert value
    Type “Microsoft.SharePoint.Client.AttachmentCreationInformation”
    “Microsoft.SharePoint.Client.AttachmentCreationInformation” to type
    “Microsoft.SharePoint.Client.AttachmentCreationInformation”. ”

    can u help me?

    • Just restart the PowerShell ISE – That solves the problem!

  • Kudos – this worked almost exactly as I wanted. In my case I wanted my AttachmentPath to reference an online document, which did not work. It only worked when my documents was local. Other than that, it worked perfectly.

  • I am getting error on 49thline.

    Exception calling “ExecuteQuery” with “0” argument(s): “parameters
    Parameter name: Specified value is not supported for the parameters parameter.”
    At line:36 char:13
    + $Ctx.ExecuteQuery()
    + ~~~~~~~~~~~~~~~~~~~

    If I remove the line, script has been ran successfully.
    But File has not been uploaded.Please help.


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