Redmine

When I try to add a file that has umlauts in its filename, the file upload returns error 500

ruby 2.2.0p0 (2014-12-25 revision 49005) [x86_64-linux]

ActiveRecord::StatementInvalid (Mysql2::Error: Incorrect string value: '\xCC\x88uft....' for column 'filename' at row 1: INSERT INTO `attachments` (`filesize`, `author_id`, `filename`, `content_type`, `created_on`, `disk_directory`, `disk_filename`, `digest`) VALUES (104227, 2, 'FileWithÄ.png', 'image/png', '2015-03-10 21:25:52.322050', '2015/03', '150310212552_2ee9c348b107f4bb61a9c636081148c7.png', '53487d81c5beb80ef2f4e3658f4326da')):
app/controllers/attachments_controller.rb:90:in `upload'