Powershell script to edit SPO site secondary owner using property bag values

In SharePoint Online (SPO) we cannot modify the secondary owner using SharePoint Hosted Apps so there is a work around to modify this value using powershell script.
We can save the secondary owner values in property bag and then using powershell we can update secondary owner field.

Add-Type -Path "C:\Program Files\Common Files\microsoft shared\Web Server Extensions\15\ISAPI\Microsoft.SharePoint.Client.dll"  
Add-Type -Path "C:\Program Files\Common Files\microsoft shared\Web Server Extensions\15\ISAPI\Microsoft.SharePoint.Client.Runtime.dll"  

#Log File
$DatePostFix = Get-Date -format "MM-dd-yyyy_hh-mm-ss"
$LogFileName = "SetSecondaryOwner_SPO_" + $DatePostFix + ".csv"
$LastRunDateFileName = "SetSecondaryOwner_SPO_LastRunDate.csv"
# User Credentials
$Username="abc@org.com" 
$AdminPassword = Read-Host -Prompt "Enter Password" -AsSecureString

## Site URL - Providing the credentials
$AdminUrl="https://sposite.sharepoint.com"

#Retrieve all site collection infos
$cred = New-Object -TypeName System.Management.Automation.PSCredential -ArgumentList $Username, $AdminPassword
Connect-SPOService -Url $AdminUrl -Credential $cred
$sitesCollectionsList = Get-SPOSite 

try 
{
    # Get todays date. 
        $todayDate = Get-Date 

    # Get Script last run date
        if (!(Test-Path $LastRunDateFileName))
        {
            "{0}" -f $todayDate.AddDays(-1) |Add-Content $LastRunDateFileName  
        }
        $lastRunFile = Get-Content $LastRunDateFileName
        if ([string]::IsNullOrEmpty($lastRunFile)) {            
            $scriptLastRundate = $todayDate.AddDays(-1).ToString()
        }
        else
        {
            $scriptLastRundate = [datetime]$lastRunFile.ToString()
        }

    #Retrieve and print all sites
    foreach ($siteColl in $sitesCollectionsList)
    { 
    
      try
      {

        #SPO Client Object Model Context
        $ctx=New-Object Microsoft.SharePoint.Client.ClientContext($siteColl.Url)
        $ctx.Credentials = New-Object Microsoft.SharePoint.Client.SharePointOnlineCredentials($Username, $AdminPassword)
        $site=$ctx.site
        $spoRootWeb = $ctx.Web
        $ctx.Load($site)
        $ctx.Load($spoRootWeb)
        $ctx.ExecuteQuery()
        
        #Get the property bag values 
        $spoAllSiteProperties=$spoRootWeb.AllProperties
        $ctx.Load($spoAllSiteProperties)
        $ctx.ExecuteQuery()  
        
        # Check if Last Review date exist and get the value
        $lastReviewdate = ""
        if ($spoAllSiteProperties.FieldValues.ContainsKey(‘__reviewedOn_key___’)) {
            $lastReviewdate = [datetime]$spoAllSiteProperties[‘__reviewedOn_key___’]
        }

        # Update Secondary Owner if lastreview date is today's date or script last run date is lesser than the review date
        if (!([string]::IsNullOrEmpty($lastReviewdate))) {
            if (($scriptLastRundate -lt $lastReviewdate) -or ($lastReviewdate.ToShortDateString() -eq $todayDate.ToShortDateString()))
            {
                if(($spoAllSiteProperties.FieldValues.ContainsKey(‘__secondary_contact__’)) -and ($spoAllSiteProperties["__secondary_contact__"] -ne ""))
                {
                    
                $sUser = $site.RootWeb.EnsureUser($spoAllSiteProperties[‘__Secondary_Contact__’]);
                $ctx.Load($sUser);
                $ctx.ExecuteQuery()  

                # Update secondary contact
                $site.SecondaryContact = $sUser
                $site.SecondaryContact.Update();
                $ctx.ExecuteQuery();              

                }

                $ctx.Dispose()
             }
           }
        }
        Catch [exception]
        { 
            # Logging the exception in log file
            "{0},{1}" -f "Error in SetSecondaryOwner SPO script while traversing in each sitecollection. Site URL= $site.Url", $_.Exception.Message |Add-Content $LogFileName    
        }        

     }

      #Update Last Run Date CSV for script last run date
       Clear-Content $LastRunDateFileName
       "{0}" -f $todayDate |Add-Content $LastRunDateFileName  

 }
 Catch [exception]
   { 
            # Logging the exception in log file
            "{0},{1}" -f "Error in SetSecondaryOwner SPO script.", $_.Exception.Message |Add-Content $LogFileName    
   }
 finally
   {
            $ctx.Dispose()
   }