Hi, I have a mongrel cluster with a mongrel_upload_progress ... when I upload a file, my cookie session id changes .... So on the upload form, my Session ID is say: BAh7ByIKZmxhc2hJQzonQWN0aW9uQ29udHJvbGxlcjo6Rmxhc2g6OkZsYXNo%0ASGFzaHsABjoKQHVzZWR7ADoOcmV0dXJuX3RvIj8vdXBsb2FkL25vdz91cGxv%0AYWRfaWQ9M2Q0MzJiN2UtYWUxYy0xMWRjLTgzNDEtMDAxNTE3NGE0NDVj--9a36dd5853f963386ba042995bf66630c0b5734f And when I do my multi-part form POST, after Mongrel''s dealt with the whole upload and passes the request on to Rails, my session has changed to: BAh7ByIKZmxhc2hJQzonQWN0aW9uQ29udHJvbGxlcjo6Rmxhc2g6OkZsYXNo%0ASGFzaHsABjoKQHVzZWR7ADoOcmV0dXJuX3RvIj8vdXBsb2FkL25vdz91cGxv%0AYWRfaWQ9M2M4ZmM5YzQtYWUxOS0xMWRjLThlMWItMDAxNTE3NGE0NDVj--13fb2eb052168b2860bac39b2d14839bb9ed6979 Normal requests after that revert back to the initial Session ID ... You can see that just that last portion changes. If I don''t run a cluster - ie on my development machine, it works fine. Why is that? The effect is that my user is not logged in for the upload post ... which means the filter chain redirects me to log in. :-( Thanks Joerg -- Posted via http://www.ruby-forum.com/.