Enable modern site pages

Hi 

Below powershell script worked for me.. I got it from microsoft technical team.

# Load SharePoint Online Client Components SDK Module
Import-Module 'C:\Program Files\Common Files\microsoft shared\Web Server Extensions\16\ISAPI\Microsoft.SharePoint.Client.dll'

# Set script constants
$sitePagesFeatureIdString = 'B6917CB1-93A0-4B97-A84D-7CF49975D4EC'

# Set up client context
$userName = Read-Host "Username"
$password = Read-Host "Password" -AsSecureString
$siteUrl = Read-Host "Site Url"
$webUrl = Read-Host "Server-Relative Web Url"
$context = New-Object Microsoft.SharePoint.Client.ClientContext($siteUrl)
$credentials = New-Object Microsoft.SharePoint.Client.SharePointOnlineCredentials($userName, $password)
$context.Credentials = $credentials

# Get the list of existing features
$web = $context.Site.OpenWeb($webUrl)
$features = $web.Features
$context.Load($features)
$context.ExecuteQuery()

# Verify that the Site Pages feature is not present in the web
if(($features | ? { $_.DefinitionId -eq $sitePagesFeatureIdString }).Count -gt 0)
{
Write-Host "The Site Pages feature is already enabled in this web"
return
}

# Add the Site Pages feature back to the web
$features.Add((new-object 'System.Guid' $sitePagesFeatureIdString), $false, [Microsoft.SharePoint.Client.FeatureDefinitionScope]::None)
$context.ExecuteQuery()

# Verify that the Site Pages feature is now present in the web
$web = $context.Site.OpenWeb($webUrl)
$features = $web.Features
$context.Load($features)
$context.ExecuteQuery()

if(($features | ? { $_.DefinitionId -eq $sitePagesFeatureIdString }).Count -gt 0)
{
Write-Host "The Site Pages feature has been successfully enabled"
}
else
{
throw "The Site Pages feature failed to be enabled"
}