Redmine

When I tried to delete project in Administratoion/Projects after confirmation I received an error Redmine 500 error.
In /var/www/redmine/log/production.log there are the following:

Started DELETE "/projects/x01" for 192.168.204.49 at Fri Jan 24 11:22:43 +0400 2014
Processing by ProjectsController#destroy as HTML
Parameters: {"authenticity_token"=>"/D91RCipYv10ilE/09o4HOJ8NytS8c3rlIdObYFcu8M=", "id"=>"x01"}
Current user: rifle (id=1)
Rendered projects/destroy.html.erb within layouts/base (6.8ms)
Completed 200 OK in 44.3ms (Views: 32.5ms | ActiveRecord: 4.0ms)
Started DELETE "/projects/x01" for 192.168.204.49 at Fri Jan 24 11:22:45 +0400 2014
Processing by ProjectsController#destroy as HTML
Parameters: {"commit"=>"Delete", "utf8"=>"✓", "confirm"=>"1", "authenticity_token"=>"/D91RCipYv10ilE/09o4HOJ8NytS8c3rlIdObYFcu8M=", "id"=>"x01"}
Current user: rifle (id=1)
Completed 500 Internal Server Error in 482.0ms

NoMethodError (undefined method `children' for nil:NilClass):
app/models/issue.rb:165:in `create_or_update'
app/models/issue.rb:1371:in `recalculate_attributes_for'
app/models/issue.rb:1334:in `update_parent_attributes'
app/models/issue.rb:179:in `destroy'
lib/plugins/awesome_nested_set/lib/awesome_nested_set/awesome_nested_set.rb:455:in `destroy_descendants'
lib/plugins/awesome_nested_set/lib/awesome_nested_set/awesome_nested_set.rb:453:in `destroy_descendants'
lib/plugins/awesome_nested_set/lib/awesome_nested_set/awesome_nested_set.rb:426:in `in_tenacious_transaction'
lib/plugins/awesome_nested_set/lib/awesome_nested_set/awesome_nested_set.rb:443:in `destroy_descendants'
app/models/issue.rb:179:in `destroy'
app/controllers/projects_controller.rb:236:in `destroy'

Unfortunately I can't find the solurion in the internet. Redmine version 2.4.2