On the site I'm working on it used to run in an older version of Windows/IIS. We upgraded the server and it's now on Windows 7, IIS 7, and is running on an ASP.NET v4.0 app pool (i.e. not the default app pool but still a .net generated app pool). When the upgrade happened we copied some files the users uploaded to the new server. Now IIS can't delete the older files. If I upload a new file everything works fine though.
I noticed that if I go to the Properties > Details of the files the copied file has some other user as the owner and the uploaded file has "ASP.NET v4.0" as the owner. I can't change the owner to the asp.net 4 user though because it can't be found when I try to change it.
Is there some way to give the "ASP.NET v4.0" user permissions to all files in my uploaded files directory? I know that there is some weirdness with the way IIS app pool users sort-of-exist but I don't fully understand that yet.