How to Fix Missing or Duplicate Pages in an eTextbook PDF

Missing or duplicate pages usually come from one of four places: the reader's page map, an incomplete official export, content that did not finish loading, or a page-turn failure in a permitted screenshot sequence.

Short answer: Record the first and last bad page, identify how the PDF was created, fix that cause, and regenerate only the affected permitted range.

Do not confuse PDF index with textbook page number

A PDF viewer counts every page from the first file page. A textbook may use Roman numerals for the preface, omit numbers on chapter openers, or begin printed page 1 after many front-matter pages.

Create a small map:

Compare visible labels, chapter headings, and content. A numbering offset is not a missing page.

If the PDF came from the reader's official export

Check:

• the first and last page entered;
• whether the range uses printed pages or reader locations;
• print history and remaining allowance;
• an error or timeout during conversion;
• whether the title itself omits or combines page labels;
• whether notes were printed on separate pages.

Open the smallest allowed test around the boundary. If the service counted a failed job against the allowance, contact support before trying again. Send the title, ISBN, requested range, result, and print history.

RedShelf and BibliU both generate PDFs through their own systems. Their support teams can inspect a failed conversion in a way a browser cannot.

If the PDF came from browser Print

The browser may omit canvas-based pages, content hidden by print CSS, or sections not loaded into the document.

Return to print preview and look for the missing page there. If it is absent in preview, do not expect the saved PDF to contain it. Use the reader's official print feature or ask support.

If the page is present but clipped, adjust paper orientation, scale, and margins. Test a small range.

If the PDF came from permitted screenshots

Use this section only for material you own, created, openly licensed, or have explicit permission to capture.

Common causes are:

Run a three-to-five-page test that includes a normal turn, chapter boundary, and image-heavy page. Do not start a long session until each transition is correct.

Rebuild only the affected range

Once the cause is fixed:

1. Start one good page before the problem.
2. End one good page after it.
3. Regenerate that small permitted range.
4. Compare the overlap pages.
5. Insert the corrected pages and remove the bad copies.
6. Save a new version rather than overwriting the only source.

The overlap makes it easier to verify that no transition was lost.

Replace the bad pages in Preview on Mac

Apple's Preview guide confirms that you can add, delete, move, and drag pages between PDFs. Preview saves edits automatically, so preserve the original first.

1. Open the main PDF and choose File > Duplicate.
2. Open the corrected-range PDF in a second Preview window.
3. In both files, choose View > Thumbnails.
4. Drag the corrected page thumbnails into the duplicate, next to the bad range.
5. Compare the overlap page before and after the insertion.
6. Select the bad thumbnails and press Delete.
7. Drag any remaining thumbnail into the correct order.
8. Save with a new name, then reopen it and verify the two boundaries.

If the original pages contain Preview annotations, remember that deleting a page also deletes its annotations. Move or recreate any annotations you need before deleting the bad page.

Verify with thumbnails and content landmarks

Page labels alone can repeat or disappear. Check:

• chapter titles;
• running headers;
• figure and table numbers;
• problem numbers;
• paragraph endings and beginnings;
• diagrams that span two pages;
• notes or highlights near the boundary.

Keep a simple QA log

For important study material, record:

Source: title, edition, ISBN
Method: official print / browser print / permitted screenshots
Expected range: 44-61
Verified: 44-61, figure 3.2 present
Fixed: duplicate page 52 replaced
Date: 2026-08-09

This is faster than rediscovering the same boundary problem later.

FAQ

Why do PDF and textbook numbers differ?

Front matter and unnumbered pages offset the PDF index. Compare visible labels and chapter content.

Why did an official export skip pages?

The range, page map, conversion, or allowance may be responsible. Check print history and contact support before retrying.

Why did screenshots repeat a page?

The reader may have lost focus, missed the keypress, or failed to load in time.

Should I rebuild the whole PDF?

No. Fix and replace only the smallest affected permitted range.