Inside the Gantt screen:

[kulesa]

Inside the Gantt screen:

[LuisSerrano]

if I delete the lines 19-20 and 31-49 redmine works fine, It's something about the relations

[LuisSerrano]

sorry I accidentally closed the issue

[LuisSerrano]

Solved I think, I modify the file issues_helper.rb the methods unless issue.relations_to.empty? and unless issue.relations_from.empty? with two ifs if (rel.issue_from) and if (rel.issue_to)

unless issue.relations_to.empty?
  content += "<br />" + issue.relations_to.first(display_limit).map do |rel|
  if (rel.issue_from)
    "<strong>#{l(rel.label_for(issue))}</strong>: #{link_to_issue(rel.issue_from)}"
  end 
  end.join("<br />")
  display_limit -= issue.relations_to.count 
end

unless issue.relations_from.empty?
  new_limit = display_limit < 0 ? 0 : display_limit
  content += "<br />" + issue.relations_from.first(new_limit).map do |rel|
    if (rel.issue_to)
       "<strong>#{l(rel.label_for(issue))}</strong>: #{link_to_issue(rel.issue_to)}"
     end
  end.join("<br />")
  display_limit -= issue.relations_from.count
end