instructure/canvas-lms · error · ImportError

Cannot move # # because it has # _memberships.

Error message

Cannot move #{type_display_name(item_type)} #{item_id} because it has #{item_type}_memberships.

What it means

Raised by can_change_context? when an existing group or differentiation tag with memberships would be moved to a different context in a disallowed way: any move of a populated differentiation tag, and any populated-group move involving a Course context (source or destination). This protects membership integrity during SIS imports.

Solutions

Remove or reassign the item's memberships before moving it.
Create a new group in the target context instead of moving the populated one.
For groups, allow only non-Course context changes (account reorganization).
Exclude the offending rows from the batch.

Example fix

# before: moving populated group to another course
group.context = new_course
group.save
# after
group.group_memberships.destroy_all
group.context = new_course
group.save

Defensive patterns

Strategy: try-catch

Validate before calling

if item.group_memberships.exists? &&
   (new_context.is_a?(Course) || item.context.is_a?(Course) || item_type == 'differentiation_tag') &&
   (new_context.id != item.context_id || new_context.class.base_class.name != item.context_type)
  raise ArgumentError, 'cannot move item with memberships'
end

Try / catch

begin
  importer.add_group(gid, cat_id, acct_id, course_id, name, status)
rescue ImportError => e
  if e.message.start_with?('Cannot move')
    logger.warn("Skipped move of populated item #{gid}")
  else
    raise
  end
end

Prevention

Avoid reassigning context for populated groups/tags in re-imports
Create new items in target contexts instead of moving populated ones
Diff incoming CSV context columns against current item context
Clear memberships deliberately before any move

When it happens

Trigger: add_group/add_tag updating an existing item (matched by sis id) whose group_memberships exist, where new_context differs from item.context and (either context is a Course, or item_type == 'differentiation_tag').

Common situations: Re-importing a groups.csv that reassigns a populated study group to another course; reorganizing account hierarchy with member-bearing groups; moving tags between courses mid-term.

Understand the failure class

Background: "Invalid state transition" errors: "status must be X, actually Y", "already rejected/charging/uninstalled", "cannot ... while running" — what they mean when a library rejects your call — this error's family across 31 libraries.

Related errors

AI-assisted analysis of instructure/canvas-lms@1c9f0bb801 (2026-09-15). Data as JSON: /api/errors/5b4659e33c2bf12e. Report an issue: GitHub.

Appendix: source

Thrown at lib/sis/group_importer.rb:147

          msg += item.errors.full_messages.join(",") + ")"
          raise ImportError, msg
        end
      end

      def can_change_context?(item, new_context, item_type, item_id)
        if item_type == "differentiation_tag"
          raise ImportError, "Differentiation Tags are not enabled for Account #{context.account.id}." unless new_context.account.allow_assign_to_differentiation_tags?
        end

        return true unless item&.group_memberships&.exists?

        same_context = new_context.id == item.context_id &&
                       new_context.class.base_class.name == item.context_type

        # For groups, we only block moves between courses, but allow other context changes
        if !same_context &&
           ((item.context.is_a?(Course) || new_context.is_a?(Course)) || item_type == "differentiation_tag")
          raise ImportError, "Cannot move #{type_display_name(item_type)} #{item_id} because it has #{item_type}_memberships."
        end

        true
      end

      public

      def add_group(group_id, group_category_id, account_id, course_id, name, status)
        return if invalid_import_item?(group_id, name, status, "group")

        if course_id && account_id
          raise ImportError, "Only one context is allowed and both course_id and account_id where provided for group #{group_id}."
        end

        context = find_context(account_id, :account_id, "group", group_id) if account_id
        context ||= find_context(course_id, :course_id, "group", group_id) if course_id

        group_category = nil

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