I have a jsp page to upload some files..
The session is used to store a Map ( session.setAttribute("filemap", filemap ) ). This map contains all the files to be uploaded. I have a file-input type, onChange the file here is added to the map. The map is stored in the session and when the page is reloaded, all files in the map can be displayed. Then the user clicks upload, and all the files are uploaded somewhere by some other code.
This works perfectly on my local machine/local host -- on the server however, i've encountered this problem...
When I browse for a file to upload and select it (with the file-input) and the page reloads - files of small file-size will work fine. The page will re-load, the item will be added to the map and displayed on the page. When I select a file with a larger file-size (even 200KB), the page shows a 'page not found' error when it reloads. I'm guessing the session on the server cant hold much space!
Does anyone know how I can get around this? Any help is appreciated!

The page not found error is normally thrown when the container fails to find the file. It AFAIK, is in no way related to the session space since the session is limited by the amount of physical memory your server machine has.

Without more code or explanation, it would be difficult to be of any further help.

the files themselves aren't stored in the session, only references to the objects containing them are.
You could of course run out of server memory causing the server to crash.
More likely you're just running into timeouts causing the browser to think the server isn't there.