"The URL is invalid" error when you browse to a SharePoint site (KB5023406)

Applies To
SharePoint Server Subscription Edition SharePoint Server 2019 SharePoint Server 2016 SharePoint Foundation 2013 SP1

Symptoms

After you install the December 2022 or January 2023 security updates for SharePoint Server, you might not be able to browse to a SharePoint website if the site URL ends in a string that matches a blocked file type extension for that web application. When you browse to such a site, you might receive the following error message:

Note

The URL '/sitename' is invalid. It may refer to a nonexistent file or folder, or refer to a valid file or folder that is not in the current Web.

Resolution

To fix this issue, install the following security update, as appropriate: