Redmine

Hi Dears,
Recently upgraded from Redmine 2.6.0 to 2.6.1
Dmsf plugin was unsuccesfull in 2.6.0 (even could not install)
In 2.6.1. it is successfully installed/migrated but following actions results Argument Error
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head to Administration>Plugins>Configure:

ArgumentError (undefined class/module ActionController::Parameters):
  app/models/setting.rb:97:in `value'
  app/models/setting.rb:110:in `[]'
  app/models/setting.rb:139:in `plugin_redmine_dmsf'
  app/controllers/settings_controller.rb:69:in `plugin'

---------------------------------------------------------------------------------
Enable project module DMSF from Project>Settings Ok, head Go to DMSF tab

ArgumentError (undefined class/module ActionController::Parameters):
  app/models/setting.rb:97:in `value'
  app/models/setting.rb:110:in `[]'
  app/models/setting.rb:139:in `plugin_redmine_dmsf'

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mysql> select value from settings where name = 'plugin_redmine_dmsf';

--- !ruby/hash:ActionController::Parameters
dmsf_max_file_upload: '0'
dmsf_max_file_download: '0'
dmsf_max_email_filesize: '0'
dmsf_max_ajax_upload_filesize: '100'
dmsf_storage_directory: /usr/share/redmine/files/dmsf
dmsf_default_notifications: ''
dmsf_display_notified_recipients: ''
dmsf_webdav: '1'
dmsf_webdav_strategy: WEBDAV_READ_ONLY
dmsf_index_database: ''
dmsf_stemming_lang: turkish
dmsf_stemming_strategy: STEM_NONE

How can i solve this problem?

Thanks and Best Regards.