If your site was migrated from SharePoint 2010 to SharePoint Online, for the time being you can still use the old URL (ex: [site_name] or [site_name]) but will be redirected to the new URL, formatted like this:
If your site was migrated from SharePoint 2010 to SharePoint Online, for the time being you can still use the old URL (ex: [site_name] or [site_name]) but will be redirected to the new URL, formatted like this: