instructure/canvas-lms · error · PeerReview::InvalidDatesError

Peer review override due date cannot be before parent…

Error message

Peer review override due date cannot be before parent override due date

What it means

PeerReview::InvalidDatesError from the parent due_at <= child due_at check (line 176-178) in validate_dates_within_parent_boundaries: peer reviews must be due no earlier than the parent assignment/override due date. For overrides the message is 'Peer review override due date cannot be before parent override due date'; the non-override variant is 'Peer review due date cannot be before assignment due date'. This enforces the documented chain assignment due <= peer review due.

Solutions

1. Raise the peer review due_at to a timestamp >= parent (override) due_at
2. Or move the parent due_at earlier so the intended peer review ordering is valid
3. If the workflow needs reviews before the assignment due date, note this ordering is not allowed — redesign dates to parent due <= review due
4. Pre-validate: raise if parent.due_at && child.due_at && parent.due_at > child.due_at

Example fix

// before
parent_due = '2026-05-10T00:00:00Z'; peer_review_due = '2026-05-05T00:00:00Z'
// after
parent_due = '2026-05-10T00:00:00Z'; peer_review_due = '2026-05-12T00:00:00Z'

def review_due_not_before_parent_due?(parent, pr_dates)
  return true if parent.due_at.nil? || pr_dates[:due_at].nil?
  parent.due_at <= Time.zone.parse(pr_dates[:due_at].to_s)
end

begin
  validator.validate_override_dates_against_parent_override(pr_override, parent_override)
rescue PeerReview::InvalidDatesError => e
  if e.message.include?('cannot be before parent override due date') || e.message.include?('before assignment due date')
    pr_override.due_at = parent.due_at + 1.day
    retry
  end
  raise
end

When it happens

Trigger: Calling validate_override_dates_against_parent_override where the parent override's due_at_overridden timestamp is later than the peer review override's due_at, or validate_peer_review_dates_against_parent_assignment where assignment.due_at > peer review due_at.

Common situations: Teacher extends the assignment due date after peer review dates were configured; API clients computing peer review due as 'assignment due minus N days' for staggered workflows (unsupported ordering); timezone shifts making the parent due appear later.

Understand the failure class

Background: "Must be a positive integer", "Invalid value", "Unsupported": the invalid-argument-value error family, when a library rejects the value you pass — this error's family across 35 libraries.

Related errors

• Parent override due date cannot be before parent override…
• Peer review due date cannot be before assignment due date
• Peer review override available from date cannot be before…
• Peer review override available from date cannot be before…
• Peer review override due date cannot be before parent…

AI-assisted analysis of instructure/canvas-lms@1c9f0bb801 (2026-09-15). Data as JSON: /api/errors/23a53d94c0822501. Report an issue: GitHub.

Appendix: source

Thrown at app/services/peer_review/validations.rb:177

    # If parent_due_at is present, validate: parent due_at <= child unlock_at
    # Otherwise, fall back to: parent unlock_at <= child unlock_at
    if parent_due_at && child_unlock_at && parent_due_at > child_unlock_at
      raise PeerReview::InvalidDatesError,
            is_override ? I18n.t("Peer review override available from date cannot be before parent override due date") : I18n.t("Peer review available from date cannot be before assignment due date")
    elsif !parent_due_at && parent_unlock_at && child_unlock_at && parent_unlock_at > child_unlock_at
      raise PeerReview::InvalidDatesError,
            is_override ? I18n.t("Peer review override available from date cannot be before parent override available from date") : I18n.t("Peer review available from date cannot be before assignment available from date")
    end

    # Validate: parent unlock_at <= child due_at (for backward compatibility)
    if parent_unlock_at && child_due_at && parent_unlock_at > child_due_at
      raise PeerReview::InvalidDatesError,
            is_override ? I18n.t("Peer review override due date cannot be before parent override available from date") : I18n.t("Peer review due date cannot be before assignment available from date")
    end

    # Validate: parent due_at <= child due_at
    if parent_due_at && child_due_at && parent_due_at > child_due_at
      raise PeerReview::InvalidDatesError,
            is_override ? I18n.t("Peer review override due date cannot be before parent override due date") : I18n.t("Peer review due date cannot be before assignment due date")
    end

    # Validate: child due_at <= parent lock_at
    if child_due_at && parent_lock_at && child_due_at > parent_lock_at
      raise PeerReview::InvalidDatesError,
            is_override ? I18n.t("Peer review override due date cannot be after parent override until date") : I18n.t("Peer review due date cannot be after assignment until date")
    end

    # Validate: child lock_at <= parent lock_at
    if child_lock_at && parent_lock_at && child_lock_at > parent_lock_at
      raise PeerReview::InvalidDatesError,
            is_override ? I18n.t("Peer review override until date cannot be after parent override until date") : I18n.t("Peer review until date cannot be after assignment until date")
    end
  end

  def validate_set_type_required(set_type)
    raise PeerReview::SetTypeRequiredError, I18n.t("Set type is required") unless set_type.present?

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