How to replace multiple certificates in IIS - windows

Question

I want to replace certificate for few websites hosted by IIS. I created Powershell script:
Import-Module Webadministration
$certname = "E:\cert.pfx"
$certpwd = "zaq12wsx"
$hostname = "test.com"
$pfxpass = $certpwd |ConvertTo-SecureString -AsPlainText -Force
$newCert = Import-PfxCertificate -FilePath $certname `
-CertStoreLocation "Cert:\LocalMachine\My" `
-password $pfxpass
# fetch the default web site:
$sites = Get-ChildItem -Path "IIS:\Sites" | where {( $_.Name -like "*$hostname" )}
foreach ($site in $sites)
{
if ($site.Bindings.Collection.protocol -eq 'https'){
$binding = $site.Bindings.Collection | `
where {( $_.protocol -eq 'https' -and $_.bindingInformation -eq '*:443:')}
$binding.AddSslCertificate($newCert.Thumbprint, "my")
}
}
But I receive error:
You cannot call a method on a null-valued expression.
At line:22 char:9
+ $binding.AddSslCertificate($newCert.Thumbprint, "my")
+ ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
+ CategoryInfo : InvalidOperation: (:) [], RuntimeException
+ FullyQualifiedErrorId : InvokeMethodOnNull
Is there an any option to replace cert for few websites with the same domain?

Answer 1

If you have several sites using the same certificate, you want to batch update the SSL certificates in these several sites via script, you can try the following method, I think it is easier to implement:
***Assign Thumbprints to Variables***
Import-Module Webadministration
$OldThumbprint = "insert thumbprint of the existing certificate here"
$NewThumbprint = "insert the thumbprint of the new certificate here"
Get-WebBinding | Where-Object { $_.certificateHash -eq $OldThumbprint} | ForEach-Object {
Write-Host "Replacing Cert For " $_
$_.RemoveSslCertificate()
$_.AddSslCertificate($NewThumbprint, 'My')
}
The result of my test was successful:
This method requires you to retrieve the thumbprints of the old and new certificates first. Then you need to copy the thumbprints of the old and new certificates and replace them in the script.
On how to retrieve the thumbprint of the certificate, you can follow the steps in this document.
On how to view certificates with the MMC snap-in, you can refer to this document.