sharepoint server – "Projects" can not be used as a site name. Site names can not contain certain reserved words and can not begin with an underscore.

The following error is displayed when I try to create a library called Projects:

"Projects" can not be used as the site name. Site names can not contain certain reserved words and can not begin with an underscore.

I have done some research and most people have solved the problem by deleting a managed path on the web application. My problem is slightly different because I have this path managed in another web application and even the deletion always gives me the same error. I thought it might be a reserved word SP2016 but I could create the same library in a development farm that I have from the company.

Here is the configuration I have on 2 farms (1 dev and 1 not prod):

Both web applications use the same generic certificate and the same application pool (I tried with different application pools, same error). The webapp2 has the "projects" defined as managed path, but I try to create the library on the webapp1 that does NOT have the path managed.

I thought that it might be a legacy of the migration, but I just rebuilt the farm with NO content and the problem persists. So I think it's up to the battery configuration (with AutoSPInstaller).