instructure/canvas-lms · error · ContentUnavailable

Page not found

Error message

Page not found

What it means

StudyAssist::ContentUnavailable with 'Page not found' is raised by resolve_page when @course.wiki_pages.not_deleted.find_by(url: page_id) returns nil. The page_id is treated as a wiki page URL slug; a non-matching or deleted page yields no record.

Solutions

  1. Pass the wiki page's url slug (not its numeric ID) as page_id
  2. Confirm the page exists and is not deleted in the target course
  3. Verify the page_id originates from the same @course the service is constructed with
  4. Query WikiPage.not_deleted.where(url: page_id) in console to debug the lookup

Example fix

// before
StudyAssist.new(course: @course, user: @user, prompt:, page_id: page.id).call
// after
StudyAssist.new(course: @course, user: @user, prompt:, page_id: page.url).call
Defensive patterns

Strategy: validation

Validate before calling

page = course.wiki_pages.not_deleted.find_by(url: page_id)
raise StudyAssist::ContentUnavailable, 'Page not found' if page.nil?

Type guard

null

Try / catch

begin
  StudyAssist.new(course:, user:, prompt:, page_id: page_id).call
rescue StudyAssist::ContentUnavailable => e
  render json: { error: e.message }, status: :not_found
end

Prevention

When it happens

Trigger: Calling #call with page_id that doesn't match any non-deleted wiki page's url in the course (typo'd slug, page deleted, page belongs to another course, or a numeric ID passed where a URL slug is expected).

Common situations: Frontend passes the page's numeric ID instead of its url slug; stale client cache referencing a deleted page; cross-course copy where the slug differs; hidden/wiki pages with different url attribute than title.

Understand the failure class

Background: Record Not Found Errors: "not found", RecordNotFound, and "was not found" — what they mean and how to fix them — this error's family across 28 libraries.

Related errors

AI-assisted analysis of instructure/canvas-lms@1c9f0bb801 (2026-09-15). Data as JSON: /api/errors/dc08c5852b10b2c5. Report an issue: GitHub.

Appendix: source

Thrown at app/services/study_assist.rb:158

      content =
        if page_id.present?
          resolve_page(page_id)
        elsif file_id.present?
          resolve_file(file_id)
        else
          raise ContentUnavailable, "No pageID or fileID provided"
        end

      if content.text.length > MAX_CONTENT_CHARS
        raise ContentTooLarge, "Content exceeds #{MAX_CONTENT_CHARS} character limit"
      end

      content
    end

    def resolve_page(page_id)
      page = @course.wiki_pages.not_deleted.find_by(url: page_id)
      raise ContentUnavailable, "Page not found" if page.nil?
      raise ContentUnavailable, "Page access denied" unless page.grants_right?(@user, :read)

      shard_safe_key = shard_safe_cache_key_for(page)
      text = Rails.cache.fetch(text_cache_key_for(:page, shard_safe_key), expires_in: TEXT_CACHE_TTL) do
        html_to_text(page.body.to_s)
      end

      Content.new(kind: :page, id: page.id, cache_key_with_version: shard_safe_key, text:)
    end

    def resolve_file(file_id)
      attachment = @course.attachments.find_by(id: file_id)
      raise ContentUnavailable, "File not found" if attachment.nil? || attachment.deleted?
      raise ContentUnavailable, "File access denied" unless attachment.grants_right?(@user, :read)
      raise ContentUnavailable, "File is locked" if attachment.locked_for?(@user, check_policies: true)
      raise UnsupportedContentType unless supported_attachment?(attachment)
      raise ContentTooLarge, "File exceeds #{MAX_FILE_BYTES} byte limit" if attachment.size && attachment.size > MAX_FILE_BYTES

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