Assume that you configure a site subscription in a web application in a Microsoft SharePoint Server 2013 farm. Then, you browse to a tenant administration site that is hosted by the web application. When you try to create a site collection in a different web application by clicking New on the tenant site, the process fails.
This behavior is by design. Each web application hosts a tenant site, and you cannot use a tenant site that is hosted by one web application to create a site collection in another web application.
To work around this issue, run PowerShell commands to create a site collection in a web application. Then, add the site collection to the site subscription that you configured. To do this, follow these steps:
Get the site subscription ID. To do this, run the following PowerShell command: Get-SPSiteSubscription
Create a site collection that subscribes to the site subscription. To do this, use the site subscription ID to run the following cmdlet:
Note For more information about the New-SPSite cmdlet, go to the following article in the Microsoft website: New-SPSite