diff -up redmine-3.2.1/app/controllers/issues_controller.rb.orig redmine-3.2.1/app/controllers/issues_controller.rb
--- redmine-3.2.1/app/controllers/issues_controller.rb.orig	2016-03-13 18:18:43.000000000 +0100
+++ redmine-3.2.1/app/controllers/issues_controller.rb	2016-06-09 17:53:20.482524185 +0200
@@ -42,6 +42,27 @@ class IssuesController < ApplicationCont
   include SortHelper
   helper :timelog
 
+  def find_optional_project
+    @project = Project.find(params[:project_id]) unless params[:project_id].blank?
+    allowed = User.current.allowed_to?({:controller => params[:controller], :action => params[:action]}, @project, :global => true)
+
+    if ! allowed and ! @project.nil?
+      @project.children.each do |subproject|
+        if User.current.allowed_to?({:controller => params[:controller], :action => params[:action]}, subproject, :global => true)
+          @project = subproject
+          return true;
+        end
+      end
+
+      @project = nil
+      allowed = User.current.allowed_to?({:controller => params[:controller], :action => params[:action]}, @project, :global => true)
+    end
+
+    allowed ? true : deny_access
+  rescue ActiveRecord::RecordNotFound
+    render_404
+  end
+
   def index
     retrieve_query
     sort_init(@query.sort_criteria.empty? ? [['id', 'desc']] : @query.sort_criteria)
diff -up redmine-3.2.1/app/views/issues/_form.html.erb.orig redmine-3.2.1/app/views/issues/_form.html.erb
--- redmine-3.2.1/app/views/issues/_form.html.erb.orig	2016-03-13 18:18:44.000000000 +0100
+++ redmine-3.2.1/app/views/issues/_form.html.erb	2016-06-08 16:36:32.921088980 +0200
@@ -8,7 +8,8 @@
 </p>
 <% end %>
 
-<% if @issue.safe_attribute?('project_id') && (!@issue.new_record? || @project.nil? || @issue.copy?) %>
+<% if @issue.safe_attribute?('project_id') #&& (!@issue.new_record? || @project.nil? || @issue.copy?)
+%>
 <p><%= f.select :project_id, project_tree_options_for_select(@issue.allowed_target_projects, :selected => @issue.project), {:required => true},
                 :onchange => "updateIssueFrom('#{escape_javascript update_issue_form_path(@project, @issue)}', this)" %></p>
 <% end %>