Hi @sns ,
Please run the below powershell script as an admin:
#Set Parameters
$AdminSiteURL="https://tenant-admin.sharepoint.com"
$SiteURL="https://tenant.sharepoint.com/sites/sitename"
#Connect to SharePoint Online Admin Center
Connect-SPOService -Url $AdminSiteURL -Credential (Get-Credential)
#Enable SharePoint Designer for the site collection
Set-SPOSite -Identity $SiteURL -DenyAddAndCustomizePages $False
Note:
Applies to: SharePoint Online
- Modern SharePoint Team Sites (attached to Office Groups)
- Modern SharePoint Communication sites (after 08/2017)
- Personal OneDrive sites
- Any SharePoint site collection created based on self-service site creation
- SharePoint Online tenant root site collection
- Any Classic SharePoint site collection
Then, please refresh the Site Settings page.You will see the SharePoint Designer Settings link.
Thanks,
Echo Du
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