Redmine › ISSUE-id

I experience the same on redmine 2.5.2.stable.

Any chance of new version of plugin and fixing this?

Fixed in this fork
https://github.com/VoronyukM/issue_id

A user reported, that the following error occurs, when a project is copied (including its issues):

Started POST "/projects/templateproject/copy" for ***.***.***.** at 2016-11-14 16:43:17 +0800
Processing by ProjectsController#copy as HTML
  Parameters: {"utf8"=>"✓", "authenticity_token"=>"q8itCbOTx4nLsJZxISEua+Y0qpqn62oaL0jgO6151OhpUjMXCuCvdT3fP5Bjhmdi0juZmUpu3QyLstbp8aSW/Q==", "project"=>{"name"=>"Test Copy Project", "description"=>"This project will be used as a template for the new ones", "identifier"=>"test-copy-project", "issue_key"=>"TESTCOPYPR", "homepage"=>"", "is_public"=>"0", "parent_id"=>"", "inherit_members"=>"0", "enabled_module_names"=>["issue_tracking", ""], "tracker_ids"=>["1", "4", "5", ""], "issue_custom_field_ids"=>["1", "2", "3", "4", ""]}, "only"=>["members", "versions", "issue_categories", "issues", "queries", "boards", "wiki", ""], "commit"=>"Copy", "id"=>"templateproject"}
  Current user: eduardo.paz (id=1)
Project#copy_issues: issue #1 could not be copied: ["Issue number has already been taken"]
Project#copy_issues: issue #2 could not be copied: ["Issue number has already been taken"]
Project#copy_issues: issue #3 could not be copied: ["Issue number has already been taken"]
Project#copy_issues: issue #4 could not be copied: ["Issue number has already been taken"]
Project#copy_issues: issue #5 could not be copied: ["Issue number has already been taken"]
Redirected to http://*******.**************.com:8080/projects/test-copy-project/settings
Completed 302 Found in 295ms (ActiveRecord: 84.2ms)
Started GET "/projects/test-copy-project/settings" for ***.***.***.** at 2016-11-14 16:43:17 +0800
Processing by ProjectsController#settings as HTML
  Parameters: {"id"=>"test-copy-project"}
  Current user: ******** (id=1)
  Rendered plugins/issue_id/app/views/projects/_key.html.erb (0.2ms)
  Rendered projects/_form.html.erb (18.6ms)
  Rendered projects/_edit.html.erb (19.3ms)
  Rendered projects/settings/_modules.html.erb (2.5ms)
  Rendered projects/settings/_members.html.erb (11.2ms)
  Rendered projects/settings/_versions.html.erb (6.2ms)
  Rendered projects/settings/_issue_categories.html.erb (6.7ms)
  Rendered common/_tabs.html.erb (47.8ms)
  Rendered projects/settings.html.erb within layouts/base (48.2ms)
  Rendered plugins/a_common_libs/app/views/hooks/a_common_libs/_html_head.html.erb (0.6ms)
Completed 200 OK in 75ms (Views: 37.0ms | ActiveRecord: 30.5ms)

Looks to be related.