Redmine

After upgrading to Redmine 2.3.3 I noticed that all my attachments are downloaded when one clicks on them. It was very convenient to view small text files in one click. What to do to restore inline view of file?

Environment:
  Redmine version                2.3.3.stable
  Ruby version                   1.9.3-p448 (2013-06-27) [i686-linux]
  Rails version                  3.2.13
  Environment                    production
  Database adapter               Mysql2
Redmine plugins:
  extended_fields                0.2.2
  redmine_all_files              0.0.3
  redmine_screenshot_paste       2.1.0
  redmine_tags                   2.0.1-dev
  sidebar_hide                   0.0.4

It seems that all new attachments, which were submitted after upgrade, have content_type=null in table 'attachments'.