Redmine

Log File :
NoMethodError (undefined method `group_by' for nil:NilClass):
app/models/issue.rb:621:in `save_issue_with_child_records'
app/models/issue.rb:613:in `save_issue_with_child_records'
app/controllers/issues_controller.rb:180:in `update'
/usr/lib/ruby/1.8/webrick/httpserver.rb:104:in `service'
/usr/lib/ruby/1.8/webrick/httpserver.rb:65:in `run'
/usr/lib/ruby/1.8/webrick/server.rb:173:in `start_thread'
/usr/lib/ruby/1.8/webrick/server.rb:162:in `start'
/usr/lib/ruby/1.8/webrick/server.rb:162:in `start_thread'
/usr/lib/ruby/1.8/webrick/server.rb:95:in `start'
/usr/lib/ruby/1.8/webrick/server.rb:92:in `each'
/usr/lib/ruby/1.8/webrick/server.rb:92:in `start'
/usr/lib/ruby/1.8/webrick/server.rb:23:in `start'
/usr/lib/ruby/1.8/webrick/server.rb:82:in `start'

Please give details on your environment (gems, plugins, etc.) according to SubmittingBugs.

Gems :
aaronp-frex (1.0.1)
actionmailer (2.3.14, 2.3.11)
actionpack (2.3.14, 2.3.11)
activerecord (2.3.14, 2.3.11)
activeresource (2.3.14, 2.3.11)
activesupport (2.3.14, 2.3.11)
Ascii85 (1.0.1)
holidays (1.0.4, 1.0.3)
i18n (0.4.2)
icalendar (1.1.6)
juggernaut (2.1.0)
nokogiri (1.5.0)
open-uri-cached (0.0.4)
pdf-reader (0.10.1)
prawn (0.12.0)
rack (1.1.2)
rails (2.3.14, 2.3.11)
rake (0.8.7)
redis (2.2.2)
ttfunk (1.0.3)

Plugins :

Redmine Backlogs
A plugin for agile teams
relaxdiego, friflaj v0.7.0 Configure
Central Panel of Management
Global and per project summarized views
Emergya Consultoría 0.9.4.1
Redmine Dnoise Workload plugin
This is a plugin for Redmine Workload
Dnoise Rafael Calleja 0.0.1
Basic project file loader for Redmine
Basic project file loader
Simon Stearn largely hacking Andrew Hodgkinsons trackrecord code (sorry Andrew) 0.0.11 Configure
Redmine Ft Import plugin
This is a project import plugin for Redmine
http://example.com/path/to/plugin
Stevan 0.0.1

Please remove all your plugins and try to reproduce with a recent version of Redmine if the problem still annoys you. As the issue is pretty old I close it but don't hesitate to reopen if you have new informations.