What causes "Improper status #{status} for a cross-listing" in instructure/canvas-lms?

Keep the regex at line 55 and the case statement branches in sync when adding statuses

instructure/canvas-lms · warning · ImportError

Improper status # for a cross-listing

Error message

Improper status #{status} for a cross-listing

What it means

A defensive fallback inside add_crosslist's case statement: if status matched neither the 'active' nor 'deleted' branch, ImportError "Improper status ... for a cross-listing" is raised. With the current regex this is largely unreachable, but it guards the case-statement against future status values added without corresponding branches.

Solutions

Keep the regex at line 55 and the case statement branches in sync when adding statuses
Add an explicit branch (or explicit rejection) for any new status value
Rely on the line-55 validation: ensure status is 'active' or 'deleted' before calling add_crosslist
Remove custom patches that inject third status values

Example fix

# before
case status
when /\Aactive\z/i then ...
when /\Adeleted\z/i then ...
else raise
end
# after
unless status =~ /\A(active|deleted)\z/i
  raise ImportError, "Improper status #{status.inspect} for a cross-listing"
end
case status
when /\Aactive\z/i then ...
when /\Adeleted\z/i then ...
end

Defensive patterns

Strategy: validation

Validate before calling

raise ArgumentError, 'status must be active or deleted' unless status.to_s.match?(/\A(active|deleted)\z/i)

Try / catch

begin
  xlist.add_crosslist(xlist_course_id, section_id, status)
rescue SIS::ImportError => e
  Rails.logger.warn("Crosslist rejected: #{e.message}")
end

Prevention

Keep the validation regex and case branches in sync when extending statuses
Avoid custom patches introducing extra status values
Cover add_crosslist with specs for each accepted status

When it happens

Trigger: A code change introduces a new accepted status in the line-55 regex (or bypasses it) but no case branch handles it; a caller monkey-patching or refactoring the validation lets an unexpected status through to the case statement.

Common situations: Custom Canvas patches/plugins extending cross-listing statuses; refactors that decouple the upfront regex validation from the case dispatch.

Understand the failure class

Background: Invalid enum value errors: "Unknown type", "Invalid scope", "must be one of" — when a string is not on the library's allowed list — this error's family across 23 libraries.

Related errors

AI-assisted analysis of instructure/canvas-lms@1c9f0bb801 (2026-09-15). Data as JSON: /api/errors/3e2f092ba367a64a. Report an issue: GitHub.

Appendix: source

Thrown at lib/sis/xlist_importer.rb:121

            rescue => e
              raise ImportError, "An active cross-listing failed: #{e}"
            end

          when /\Adeleted\z/i
            if @course && section.course_id != @course.id
              @success_count += 1
              return
            end

            begin
              @course_ids_to_update_associations.merge [section.course_id, section.nonxlist_course_id]
              section.uncrosslist(run_jobs_immediately: true)
            rescue => e
              raise ImportError, "A deleted cross-listing failed: #{e}"
            end

          else
            raise ImportError, "Improper status #{status} for a cross-listing"
          end

          @success_count += 1
        end
      end
    end
  end
end

View on GitHub (pinned to 1c9f0bb801)