After upgrading redmine 0.7.2 to 0.9, the attached files were no longer served. After some searching I verified that files are stored in
RAILS_ROOT/files
and config/boot.rb confirms that RAILS_ROOT is the redmine folder (/usr/share/redmine/config/..).
My files were indeed in the redmine/files folder. But I got a “Can’t be found error” whenever I clicked on an attached file.
After much fruitless googling and wondering why people use redmine when its so wonderfully documented, I happened upon a reference to attachment.rb (redmine/app/models/attachment.rb).