Iis – Setting Permissions in Windows Azure Website

Sounds like one or more of:
1. The home directory doesn't exist. It will not create the home directory for you.
2. The user, either anonymous (IUSR_Server) or your account (whichever is used to login), doesn't have traverse directory permission to the home directory.
3. The IP is not allowed to log in (either not allowed with the 'block all except' setting, or blocked with the 'allow all except' setting).

There is no such thing as 777 permissions on Windows. You set access to a resource by adding Access Control Entries (ACEs) to Access Control Lists (ACLs).

Assuming you are using the defaults for IIS8, you can grant write permission to the directory like this:

icacls.exe "C:\inetpub\wwwroot\uploader" /t /grant "IIS AppPool\DefaultAppPool:(OI)(CI)(M)"

The IIS application pool runs under the "IIS AppPool\DefaultAppPool" account, so you want to give it Modify permissions.

C:\inetpub\wwwroot\ should be you site root, so 'uploader' should be accessible via 'www.mysite.com/uploader'. If not check the settings of your site.