NotebookLM source upload errors almost always come from one of six causes: a file that’s too big, a PDF with no readable text, a protected file, a full notebook, a web page or video that can’t be read, or a browser problem. Once you know which one you’re dealing with, the fix usually takes a few minutes. This guide lists each error, what causes it and how to solve it. Google renamed NotebookLM to Gemini Notebook in July 2026, so you may see either name on your screen. The advice applies to both.
NotebookLM source upload errors: the short answer
Check the file against NotebookLM’s limits first, then check whether it has real text. Google’s help page says local uploads can be up to 200 MB and each source up to 500,000 words, with no page limit. Failures also come from copy-protected PDFs. If the file is within the limits and still fails, test an incognito window with extensions switched off, because ad blockers are a common hidden cause.
Key takeaways
- Each source can be up to 200 MB or 500,000 words, whichever limit you hit first.
- Scanned PDFs without a text layer often fail or import empty.
- Copy-protected PDFs are blocked, which Google confirms.
- A full notebook rejects new files, no matter how small they are. The free plan is reported to hold 50 sources per notebook.
- Websites behind paywalls and YouTube videos without captions can’t be read.
- Extensions, old cookies and the wrong Google account cause plenty of “mystery” failures.
The limits that trigger most errors
| Item | Limit | Source |
|---|---|---|
| Size of a local file | 200 MB | Google help page |
| Words per source | 500,000 | Google help page |
| Pages per PDF | No page limit | Google help page |
| Sources per notebook, free | 50 | Third-party tracker, October 2026 |
| Sources per notebook, AI Plus / Pro | 100 / 300 | Third-party tracker, October 2026 |
| Google Slides deck | About 100 slides | Third-party tracker |
| Google Sheets workbook | About 100,000 tokens in total | Third-party tracker |
The first three rows come straight from Google. The rest come from outside trackers that update often, so check your own account before you plan around them. Upgrading raises the number of sources, but it doesn’t raise the size limit for each one. Our NotebookLM explainer covers the other free limits.
Error 1: the file is too big
If a PDF is over 200 MB or a text file is over 500,000 words, the upload fails. A single dense textbook can reach that word count. Split the file into parts, for example chapters 1–10 and 11–20, and upload each part as its own source. For a PDF full of large images, “print to PDF” or a compression tool can shrink the file size without touching the text.
Error 2: the PDF is a scan with no text
A scanned document is only a set of pictures of pages. NotebookLM needs text to read, so an image-only PDF may stall or arrive empty. You can test this yourself: open the PDF and try to select a sentence with your mouse. If you can’t, there’s no text layer.
- Open the PDF in Google Drive, then choose to open it with Google Docs. Docs tries to read the text from the page images.
- Check the result for obvious mistakes and fix them. This route suits short, clear scans, because Docs limits the size and length of files it will convert. For long books, use a dedicated OCR tool.
- Download it as a PDF or add the Google Doc directly as a source.
Any good OCR tool does the same job. Poor scans, handwriting and skewed pages read badly, so expect to proofread.
Error 3: the PDF is protected
Google lists copy-protected PDFs as a reason for failure. Files with owner passwords or “no copying” settings block text extraction. If you own the document or have permission to use it, ask the author for an unprotected copy. Do not break protection on files you aren’t entitled to use. A legitimate shortcut for your own files is to export the original document again without restrictions.
Error 4: the notebook is full
Each notebook has a cap on sources. When you reach it, every new upload fails with a generic error, even a tiny text file. Two fixes help:
- Combine small files. Paste ten short notes into one document and upload that single file.
- Start a second notebook. Split your research by topic. The trade-off is that a notebook can’t search across the others.
If you use the same sources in many places, our guide to what NotebookLM does explains how to organise notebooks so they stay useful.
Error 5: websites and YouTube links fail
NotebookLM can add public web pages and YouTube videos, with limits.
- Paywalled or login-only pages can’t be read. Save the page as a PDF or copy the text into a document.
- Pages that block automated readers may fail. The same workaround applies.
- YouTube videos without captions or a transcript have nothing to import. Pick a video with captions, or paste the transcript into a text file.
- Private videos are off limits.
Error 6: Google Drive or account problems
When you add files from Drive, NotebookLM uses your signed-in account. If you have several Google accounts open, you may be signed in to the wrong one. The file then looks missing or “access denied”. Sign out, sign back in with the account that owns the file, and try again. Shared files need at least view access. Work and school accounts can also have sharing rules set by an administrator.
Error 7: audio files
Audio is transcribed into text, so the file needs clear speech. A 200 MB limit applies. Long, high-quality recordings can reach that quickly, so saving a smaller speech-only version (mono, lower bitrate) works. A recording without spoken words produces an empty transcript.
Quick fixes that solve odd failures
If your file is within the limits and the upload still hangs, the cause is often your browser. Work through these in order.
- Refresh and try again. A short outage can look like a file problem.
- Open an incognito window. Extensions don’t run there by default. If it works, an extension was blocking the upload.
- Turn off ad blockers and privacy extensions for NotebookLM, then reload.
- Clear the site’s data (cookies and cache), then sign in again.
- Create a new notebook. The old one may have hit an internal limit.
- Add the file from Google Drive instead of from your computer. It uses a different route, which sometimes works when local upload doesn’t.
- Try another browser or device. This separates a file problem from a browser problem.
Error cheat sheet
| What you see | Likely cause | First fix |
|---|---|---|
| “Error uploading source” | Size, protection or browser | Check limits, then try incognito |
| Upload spins forever | Extension or network | Disable extensions, refresh |
| Source added but empty | Scanned PDF, no text | Run OCR through Docs |
| Add button greyed out | Notebook is full | Combine files or start a new notebook |
| Website import fails | Paywall or blocked reader | Save as PDF or copy the text |
| YouTube import fails | No captions | Paste a transcript into a text file |
| Drive file not found | Wrong account or no access | Switch accounts, check sharing |
How to prepare files so they upload first time
- Prefer text-based formats: Google Docs, plain text, Word files and text PDFs.
- Give files clear names so citations are easy to read later.
- Keep each file focused on one topic.
- Remove cover pages, repeated headers and junk from scanned books if you can.
- Check that a PDF’s text is selectable before you upload it.
Once your sources are in, our Gemini prompts give you wording for useful first questions. If the sources upload fine but the audio fails, see our guide to Audio Overview problems.
Frequently asked questions
Why does NotebookLM say error uploading source?
The usual causes are a file over 200 MB or 500,000 words, a PDF with no readable text, a copy-protected file, a notebook that has reached its source limit, or a browser extension blocking the upload. Test an incognito window first, then check the file against these limits.
What is the NotebookLM file size limit?
Google’s help page says local uploads can be up to 200 MB and each source up to 500,000 words, with no page limit. Splitting a long document into chapters keeps each part inside the limits and often gives better answers.
Why is my PDF empty in NotebookLM?
It is probably a scan made of page images with no text layer. Try selecting a sentence in the PDF. If you cannot, run it through OCR, with a dedicated OCR tool or, for a short scan, by opening it in Google Docs from Drive, then upload the result.
How many sources can a NotebookLM notebook hold?
A third-party tracker updated in October 2026 reports 50 on the free plan, 100 on AI Plus, 300 on AI Pro and more on Ultra. Higher plans raise the source count, not the size limit for each source. Check your own account.
Can NotebookLM read a YouTube video without captions?
Not reliably. It works from the transcript, so a video needs captions or an available transcript. If none exists, copy a transcript from another tool into a text file and add that file as the source instead.
Why does NotebookLM fail to add a website?
Paywalled pages, login-only pages and sites that block automated readers often cannot be imported. Save the page as a PDF or copy its text into a document and upload that. Public articles with plain text usually work.
When to ask for help
If a small, clean text file fails in a brand-new notebook, in a private window, on a different browser, the problem is probably not yours. Use the feedback option in the product and describe what you tried. Google’s help page lists a support contact for NotebookLM, which is also worth keeping. More guides are in our NotebookLM section. We keep each guide independent of Google and explain our process on the how we test page. When you’re done, head back to the homepage.
Independent publication. Not affiliated with or endorsed by Google. Limits and prices change; verify in your own account.