A Powershell script to upload a TFS extension to an on-prem TFS instance with NTLM auth

TFS_UploadExt.ps1

param
(
    [string]$Server,    
    [string]$File
)

try
{
    Add-Type -Assembly "System.IO.Compression.FileSystem"
    Add-Type -Assembly "System.Xml"
    Add-Type -Assembly "System.Web"
    
    # Resolve the wildcard file name to a specific file
    
    $Files = dir $File | Sort-Object LastWriteTime -Descending
    if(-not $Files)
    {
        Write-Error "$File not found"
        exit 1
    }
    $File = $Files[0].FullName

    Write-Host "Uploading $File to $Server"
    
    # Retrieve the publisher and the package name from the XML manifest in the archive

    $Package = [System.IO.Compression.ZipFile]::OpenRead($File)
    $Manifest = $Package.Entries | ?{$_.Name -eq "extension.vsixmanifest"}

    $ManifestXML = New-Object System.Xml.XmlDocument
    $ManifestData = $Manifest.Open()
    $ManifestXML.Load($ManifestData)
    $ManifestData.Close()
    $Package.Dispose()

    $nsm = New-Object System.Xml.XmlNamespaceManager -ArgumentList $ManifestXML.NameTable
    $nsm.AddNamespace("m", "http://schemas.microsoft.com/developer/vsx-schema/2011")
    $IdElement = $ManifestXML.SelectSingleNode("/m:PackageManifest/m:Metadata/m:Identity", $nsm)
    $PackageID = $IdElement.GetAttribute("Id")
    $Publisher = $IdElement.GetAttribute("Publisher")
    
    # Prepare and send the TFS REST HTTP request

    $Package = [System.IO.File]::ReadAllBytes($File)
    $JSON = '{"extensionManifest":"' +  [Convert]::ToBase64String($Package) + '"}'

    $wc = New-Object System.Net.WebClient
    $wc.UseDefaultCredentials = $TRUE
    $wc.Headers["Content-Type"] = "application/json"
    $wc.Headers["Accept"] = "application/json; api-version=3.0-preview.1"
    $wc.UploadString($Server + "_apis/gallery/publishers/" + $Publisher.ToLower() + "/extensions/" + $PackageID, "PUT", $JSON) | Out-Null      
}
catch
{
    Write-Error $_
    if($_.Exception -and $_.Exception.InnerException -and $_.Exception.InnerException -is "System.Net.WebException")
    {
        $Resp = $_.Exception.InnerException.Response.GetResponseStream()
        $SR = New-Object System.IO.StreamReader -ArgumentList $Resp
        $RespData = $SR.ReadToEnd()
        $SR.Close()
        Write-Error $RespData
    }
    exit 1
}

A companion gist for http://rathertech.blogspot.com/2018/02/uploading-extensions-to-tfs.html

EDIT: tested on TFS Azure DevOps 2019, works as ever.