Redmine

How can I show, in which way it can be reproduced?

Environment:
and@artvertep:/$ ruby -v
ruby 1.9.2p0 (2010-08-18 revision 29036) [x86_64-linux]
and@artvertep:/$ rails -v
Rails 3.2.5

Well the hook part in the call stack makes think of a plugin behavior, do you have any plugin installed?

If yes, could you please try to reproduce with no plugins installed?

Yes, your idea about plugin was right. When I uninstall redmine_auto_watch plugin reassign works.

Can you look on plugin, please - fix about 1 line? =)
Unfortunately, I`m no ruby programmer, and don`t understand Redmine data domain.

If you can - thanks, I really need plugin functionality.

Plugin (class) code:

# Hooks to attach to the Redmine Issues.
class AutoWatchHook < Redmine::Hook::Listener
        def controller_issues_edit_before_save(context = { })
    @issue = context[:issue]
                unless @issue.watched_by?(User.current) || @issue.author == User.current
      @issue.add_watcher(User.current)
    end

    unless @issue.watched_by?(@issue.assigned_to) || @issue.author == @issue.assigned_to
      @issue.add_watcher(@issue.assigned_to)
    end
        end
end

I think trouble is in

@issue.add_watcher(@issue.assigned_to)

issue.assigned_to is Group, but User in issue.add_watcher() expected?

# And wrote:

Yes, your idea about plugin was right. When I uninstall redmine_auto_watch plugin reassign works.

Can you look on plugin, please - fix about 1 line? =)

Try the change made in commit be93aad9913dfd5cdab40c7703151aa50b7ff5ee in a fork of the original plugin... As mentioned in the commit-message this should workaround/fix the issue you're experiencing...