Oki dokei.
Searched around.. and it seems the problem is from your game version of Jamp.
The server is using the 1.01 patch. for Jedi Knight Jedi Academy.
http://jediknight3.filefront.com/file/Jedi_Knight_Academy_Patch_101;20459 <- This one.
You said you found an.. 'all patch download' Can you give me the link to it?
Also. try reinstalling JKA. Use how I said previous. Use the downloaded CD's. (Which most then likely you have them downloaded)
Then keep the CD 1 mounted. Install the patch from that link. ^
Download JAplus and install it. or however you do with it. (I forgot)
And you're good to go.
If those aren't working.. then I am not sure why the error appears.
Usually. As it seems, that appears only if the Client Version is different then the Server Version.
Hope it works.
-Eugen