Scripting.FileSystemObject.FileExists always returns false

I'm attempting to check that a file exists before including it with Server.Execute in Classic ASP. While FileExists() returns False, Server.Execute successfully executes the file. Both calls use the exact same file path.

Why does this happen and how can I work around it?

From stackoverflow

• Are you using a Network Path? If so, try without that, perhaps mapping a drive.

  AnthonyWJones : Mapped drives are not available in ASP

• I suspect you're passing a relative path (eg., "/Subfolder/Page.asp"). You'd need to Server.MapPath that for the call into FileExists - which needs an absolute path (eg., "C:\inetpub\wwwroot\Subfolder\Page.asp").

  <%
  Dim path : path = "/Admin/default.asp"
  Dim fso : Set fso = CreateObject("Scripting.FileSystemObject")
  
  If fso.FileExists(Server.MapPath(path)) Then
     Server.Execute(path)
  Else
     Response.Write "The path " & path & " does not exist."
  End If
  
  Set fso = Nothing
  %>