Redmine

Can you confirm the files are stored correctly on the server? Have a look at the files in redmine-dir/files/ and see if the file gets correctly to the server or not.

They are corrupted too :(

See in your settings if the value is maybe too low. Please also provide more information about your setup (what rails server, what ruby, rails, db, redmine versions, what db, and so on).

The settings are ok. I am using mysql-server-5.1, redmine-0.9.3-1, ubuntu 10.04, apache2.2.14, fcgid1:2.3.4-2 rails2.2.3-2

And maybe it's important i am using https protocol

Well, the only 2 things that come to mind are that MySQL 5.1 isn't officially supported by the mysql gem, so I can't say for sure that isn't the problem, but I think you should also have a look at your apache config to see there is a time limit on running cgi processes or something akin to that. IIRC the file uploads are handed off to apache and gathered afterwards by rails/redmine, so please have a look there.