I tryed to add a new application pool.
On both web server I have the unknown state. In order to see the new application pool on the iis manager I need to close and restart the manager, a simple refresh is not enough.
When I try to start the application pool I get the error:
The object identifier does not represent a valid object. (Exception from HRESULT: 0x800710D8)
After a few minutes the result is the same.
After an iisreset (and a refresh of the manager) the application pool state chenged to stopped. At this point I was able to start the application pool.
I need to do the same steps on the other web servers.
Roberto