"Site names cannot contain certain reserved words" when you create a new SharePoint Online subsite

Problem

When you try to create a new SharePoint Online subsite, you receive the following error message:

  • Site names cannot contain certain reserved words and cannot begin with an underscore. Please enter a different name.

Solution/Workaround

To work around this behavior, follow these guidelines:

  • Use a different name for the site collection.

  • Use a site name that doesn't begin with an underscore.

  • Create a subsite from another site instead of from the root or parent site by using a path that isn't a reserved path. Reserved paths are listed in the "More Information" section of this article.

More information

This issue occurs because certain paths are reserved in SharePoint Online when you create a subsite on the root or parent site collection. For Office 365 subscriptions (excluding Office 365 Small Business), the following paths are reserved, and users will encounter the error when a site is created at these locations

For Office 365 subscriptions (excluding Office 365 Small Business):

  • /search

  • /admin

  • /wpresources

  • /sites

  • /teams

  • /personal

  • /portals

In Office 365 Small Business:

  • /search

  • /wpresources

  • /sites

  • /teams

  • /personal

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