instructure/canvas-lms · error · RuntimeError

Artifact required for assessing

Error message

Artifact required for assessing

What it means

RubricAssociation#assess requires an :artifact — the object being assessed (e.g. a Submission or QuizSubmission). This guard fires when opts[:artifact] is nil/absent, so Canvas has nothing to attach the rubric assessment to. It is a fail-fast contract check before the artifact is normalized or assessment rows are created.

Solutions

1. Pass the artifact explicitly: ra.assess(user: student, assessor: assessor, artifact: submission, assessment: {assessment_type: 'grading'})
2. Resolve the Submission first and bail out early if nil: submission = assignment.submissions.find_by(user: student) or handle absence before assessing
3. For quizzes, you may pass the Quizzes::QuizSubmission itself — assess converts it internally — but it must not be nil

Example fix

// before
submission = assignment.submissions.find_by(user_id: student.id) # may be nil
rubric_association.assess(user: student, assessor: assessor, artifact: submission, ...)
// after
submission = assignment.submissions.find_by!(user_id: student.id)
raise 'submission not found' unless submission
rubric_association.assess(user: student, assessor: assessor, artifact: submission, ...)

raise 'artifact required' if opts[:artifact].nil?
rubric_association.assess(user:, assessor:, artifact: submission, assessment:)

valid = opts[:artifact].is_a?(Submission) || opts[:artifact].is_a?(Quizzes::QuizSubmission)

begin
  rubric_association.assess(opts)
rescue RuntimeError => e
  handle_missing_artifact if e.message == 'Artifact required for assessing'
end

When it happens

Trigger: Calling rubric_association.assess(user:, assessor:, assessment: {...}) without opts[:artifact]; artifact lookup returning nil before the call (e.g. Submission.find_by(...) found nothing); passing an artifact key with the wrong name so opts[:artifact] stays nil.

Common situations: Scripts automating rubric grading where the submission lookup failed silently; LTI/tool integrations constructing the assess params themselves; quiz-submission flows where the artifact was expected to be created later but assess is called first.

Understand the failure class

Background: "missing required argument" and "the following required arguments were not provided": what required-argument errors mean and how to fix them — this error's family across 20 libraries.

Related errors

• Assessment type required for assessing
• Assessor required for assessing
• assessor and assessee required
• association required
• Cannot find # for ID: #

AI-assisted analysis of instructure/canvas-lms@1c9f0bb801 (2026-09-15). Data as JSON: /api/errors/b7301553f2a0deda. Report an issue: GitHub.

Appendix: source

Thrown at app/models/rubric_association.rb:310

  def assessment_points(criterion, data)
    if criterion.learning_outcome_id && !context.feature_enabled?(:outcome_extra_credit)
      [criterion.points, data[:points].to_f].min
    else
      data[:points].to_f
    end
  end
  protected :assessment_points

  def assess(opts = {})
    # TODO: what if this is for a group assignment?  Seems like it should
    # give all students for the group assignment the same rubric assessment
    # results.
    association = self
    params = opts[:assessment]
    raise "User required for assessing" unless opts[:user]
    raise "Assessor required for assessing" unless opts[:assessor]
    raise "Artifact required for assessing" unless opts[:artifact]
    raise "Assessment type required for assessing" unless params[:assessment_type]

    if opts[:artifact].is_a?(Quizzes::QuizSubmission)
      opts[:artifact] = association_object.find_or_create_submission(opts[:artifact].user)
    end

    if association_object.is_a?(Assignment) && !association_object.grade_group_students_individually
      group, students_to_assess = association_object.group_students(opts[:artifact].student)
      if group
        provisional_grader = opts[:artifact].is_a?(ModeratedGrading::ProvisionalGrade) && opts[:assessor]
        artifacts_to_assess = students_to_assess.map do |student|
          association_object.find_asset_for_assessment(self, student, provisional_grader:).first
        end
      else
        artifacts_to_assess = [opts[:artifact]]
      end
    else
      artifacts_to_assess = [opts[:artifact]]

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