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To fix blank Puppeteer PDFs on Heroku, first determine whether Chromium failed to launch, the page was printed before it had content, or the PDF omitted only print backgrounds or fonts. These are different failures with different fixes. Check the generated file, the deployed browser setup, page readiness, and PDF options in that order; there is no single cause established for every app.
Identify what “blank” means
Before changing buildpacks or adding delays, classify the output. A file that is missing or invalid points to a different stage than a valid PDF whose page has no text. Save a diagnostic screenshot and keep the relevant launch and navigation errors while investigating.
- No file, zero-byte file, or unreadable PDF: investigate whether PDF generation completed and whether the application wrote the returned bytes to the intended path.
- Valid PDF with empty pages: check that Chromium launched, navigation succeeded, and the page had rendered its content before
page.pdf(). - Text or foreground content appears, but colors or background images do not: inspect
printBackgroundand the page’s print CSS. - Only certain characters or writing systems are missing: investigate installed fonts and glyph coverage.
A successful browser launch does not prove that the page was ready to print. Conversely, a missing Chromium executable or shared library is a launch problem, not a print-style problem.
Use a known-good PDF flow and verify page readiness
Puppeteer’s PDF guide demonstrates navigating before printing, using waitUntil: 'networkidle2', and closing the browser when finished. networkidle2 is a useful baseline, not proof that every application has finished rendering: a single-page app may hydrate, fetch data, or reveal content after network activity settles. Check the page’s final DOM or a diagnostic screenshot, and wait for an application-specific ready condition when needed. Puppeteer documents that Page.pdf() waits for fonts by default. See the Puppeteer PDF generation guide.
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This example writes the PDF only after navigation and an explicit selector check. Replace the URL and selector with values that match your app. It is intentionally diagnostic: if the selector never appears, the error helps distinguish an unready page from an empty PDF.
const puppeteer = require('puppeteer');
(async () => {
const browser = await puppeteer.launch({
args: ['--no-sandbox', '--disable-setuid-sandbox'],
});
try {
const page = await browser.newPage();
page.setDefaultNavigationTimeout(60000);
const response = await page.goto('https://your-app.example/report', {
waitUntil: 'networkidle2',
timeout: 60000,
});
if (!response || !response.ok()) {
throw new Error(`Navigation failed: ${response ? response.status() : 'no response'}`);
}
await page.waitForSelector('[data-report-ready="true"]', { timeout: 30000 });
// Keep this while diagnosing; compare it with the PDF.
await page.screenshot({ path: '/tmp/report-before-pdf.png', fullPage: true });
const pdf = await page.pdf({
path: '/tmp/report.pdf',
format: 'A4',
printBackground: true,
waitForFonts: true,
});
if (!pdf || pdf.length === 0) {
throw new Error('Puppeteer returned an empty PDF buffer');
}
} finally {
await browser.close();
}
})();For a CommonJS project, install and import the Puppeteer package used by your app. If your project uses ES modules, adapt the import syntax to its module configuration. Replace the example readiness selector with an element that appears only after the actual report data is rendered. A fixed sleep can be useful as a short diagnostic, but it is not a reliable universal readiness test.
Check Chromium launch and Heroku dependencies
If the deployed app cannot start Chromium, inspect the full launch error and confirm the executable and its required system libraries exist in the deployed environment. Puppeteer’s Heroku troubleshooting guidance says additional dependencies are needed, recommends a Puppeteer Heroku buildpack, and shows --no-sandbox in launch arguments. Treat the buildpack recommendation as third-party deployment guidance, not a guarantee that one configuration fits every Heroku app.
The example above uses --no-sandbox and --disable-setuid-sandbox, matching the common deployment pattern shown in Puppeteer’s Heroku guidance. Disabling Chromium’s sandbox has security implications; do not treat it as a universal safe setting. Follow the deployment environment’s security requirements and use it only where the runtime requires it.
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Heroku supports both classic buildpacks for Cedar-generation apps and Cloud Native Buildpacks (CNBs) for all app generations, with different configuration paths. Its buildpacks documentation, last updated September 11, 2026, also says third-party buildpacks are unsupported by Heroku and advises inspecting their source before use. Check which buildpack model your app uses and confirm that the instructions you follow apply to it.
Record the deployed browser configuration
- Record the installed Puppeteer version and the Chromium executable path and version used in deployment.
- Inspect the Heroku stack, buildpack order, build logs, and runtime launch errors.
- Compare launch arguments between local and deployed execution.
- Do not assume a version combination is supported merely because it worked locally; the available guidance does not establish one universal Puppeteer–Chromium–Heroku version matrix.
Check Puppeteer’s browser cache when Chromium is missing
A browser cache that exists during a build may not be available in the deployed slug at runtime. The jontewks Puppeteer Heroku buildpack listing describes a cache-location change for Puppeteer v19 and later and documents using a heroku-postbuild script to move the cache into the app directory. This is specific to that buildpack and its configuration; verify it against the Puppeteer version and cache path your app actually uses rather than adding it as a general Puppeteer requirement.
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The same buildpack listing identifies clearing the Heroku build cache as a possible remedy for Chrome startup or missing-library errors. Try that only when the symptoms point to stale cache or missing dependencies, then rebuild and check the logs. Clearing a cache will not make a page that renders too early become ready to print.
Prove the page has content before printing
When Chromium launches and navigation completes but the PDF is empty, check the rendered page rather than changing the browser installation first. Record the navigation response, inspect the expected text or DOM element, and take a screenshot immediately before page.pdf(). Compare that screenshot to the PDF:
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- Screenshot has content, PDF does not: inspect print CSS, PDF options, and whether the visible content is hidden or altered for print.
- Some data is absent from both: verify that the page’s data request succeeded and that your readiness selector is tied to completed data rendering, not merely initial page load.
The Puppeteer guide’s networkidle2 example is a starting point. For applications that render after an API response or client-side hydration, wait for a meaningful element or application state. Avoid treating a longer fixed delay as a guaranteed fix: it can mask timing issues, waste runtime, and still fail under different load conditions.
Inspect PDF options, print CSS, and fonts
Puppeteer’s current PDFOptions reference lists printBackground as false by default and waitForFonts as true. It also documents paper format, page ranges, timeout, and the precedence of CSS page size. Check the documentation for the release matching your installed package because these APIs and defaults can change.
| What is missing | What to inspect | Practical check |
|---|---|---|
| Background colors or images only | printBackground and print styles |
Set printBackground: true and inspect @media print rules. |
| Text and foreground content too | Navigation, rendering readiness, runtime errors, and PDF generation | Compare the pre-PDF screenshot and DOM with the generated file. |
| Unexpected page size or clipped content | format, CSS @page size, margins, and page ranges |
Check whether CSS page-size settings take precedence for your chosen options. |
| Missing Chinese, Japanese, or Korean glyphs | Fonts available in the deployed environment | Check installed font coverage; Puppeteer’s Heroku guidance notes that a buildpack with additional fonts may be required. |
Do not assume printBackground: true repairs an entirely empty page: it controls background printing, not whether your app loaded content. Likewise, waitForFonts being enabled by default does not install missing font files or add glyphs the system font set does not contain.
Diagnose the pipeline in order
- Classify the artifact. Confirm the file exists, has nonzero size, opens as a PDF, and has the expected page count. Determine whether text is absent or only backgrounds and styling are missing.
- Compare local and deployed execution. Record Puppeteer version, Chromium path and version, Heroku stack/buildpack setup, and launch arguments.
- Verify browser launch. Inspect deployment logs and confirm required Chromium dependencies are installed. Apply Heroku-specific launch or buildpack guidance only when it fits your app’s setup.
- Check the browser cache. If the executable is missing, compare your actual cache location and Puppeteer version with the instructions for the buildpack in use. Clear and rebuild only when the symptoms support a cache or dependency problem.
- Check readiness. Verify the final URL, navigation response, rendered DOM, expected text, and diagnostic screenshot before printing.
- Inspect print behavior. Review
printBackground, fonts, format, page ranges, margins, and print CSS against the installed Puppeteer version’s API documentation. - Retain diagnostics and close resources. Keep the launch/navigation error and screenshot with the failing output while debugging, then close the browser in a
finallyblock as in the example.
Common errors and fixes
“Could not find Chrome” or executable launch failure
The deployed app may not have a usable browser at the expected path, or the browser cache may not have made it into the slug. Confirm the executable path and cache location for the installed package and deployment configuration. If using the jontewks buildpack, check its version-specific cache instructions rather than assuming they apply to every setup.
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Missing shared library or browser exits at startup
This points toward deployment dependencies or a mismatched browser environment, not print CSS. Read the complete runtime error and build logs, verify the needed dependencies for your chosen Heroku stack, and assess the applicable buildpack guidance. If using a third-party buildpack, inspect its source and remember that Heroku does not support third-party buildpacks.
PDF is valid but empty while the screenshot is empty
Check whether navigation reached the intended page, whether authentication or redirects changed the destination, whether application data loaded, and whether a JavaScript error prevented rendering. Wait for an app-specific ready condition, then capture the diagnostic screenshot again.
Screenshot is correct but the PDF loses colors or background images
Set printBackground: true and inspect print-specific CSS. Compare other PDF settings with the options supported by your installed Puppeteer version.
Only CJK characters or selected symbols are missing
Check that the deployed environment has fonts with the required glyphs. Puppeteer’s Heroku troubleshooting page notes that Chinese, Japanese, or Korean rendering may require a buildpack that supplies additional fonts.
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Compare the deployed stack, browser executable and version, buildpack configuration, cache path, fonts, and launch arguments with local execution. A successful local PDF does not establish that the deployed environment contains the same browser dependencies or fonts.
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PDF generation requires launching a browser, loading the page, waiting for its content, and printing. A readiness check should be specific enough to prevent premature output without waiting indefinitely. Set navigation and selector timeouts deliberately, log the stage that failed, and close the browser even when navigation or printing throws. Puppeteer’s example closes the browser after PDF generation; the finally pattern above also closes it when an earlier step fails.
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Keep diagnostic screenshots and logs during investigation, but avoid logging credentials, authorization headers, or sensitive page contents. Do not add repeated cache-clearing builds or longer delays without evidence: neither addresses every failure mode, and extra waits can increase job duration without fixing missing dependencies, absent fonts, or print CSS.
Or skip the browser setup
If your task is to capture a website as an image or PDF rather than generate a PDF inside your own Puppeteer deployment, ScreenshotNeo is a website screenshot API and MCP server from Yorker Media. A single GET request can return a PNG, JPEG, WebP, or PDF. For this Heroku how-to, the Puppeteer diagnosis above remains the right path when your own application must render its page and control its print workflow.
cURL example, using the documented endpoint and parameters (see the ScreenshotNeo API documentation):
curl -G "https://api.screenshotneo.com/v1/shot" -d access_key=YOUR_API_KEY --data-urlencode url=https://stripe.com -o shot.webpReplace YOUR_API_KEY and the target URL with your own. The corresponding Python example is:
import requests
r = requests.get(
"https://api.screenshotneo.com/v1/shot",
params={"access_key": "YOUR_API_KEY", "url": "https://stripe.com"},
timeout=90,
)
open("shot.webp", "wb").write(r.content)And Node.js:
const q = new URLSearchParams({ access_key: 'YOUR_API_KEY', url: 'https://stripe.com' });
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Does networkidle2 guarantee that a Puppeteer page is ready to print?
No. It is a documented navigation example and a useful baseline, but client-side hydration or delayed application data may require waiting for an app-specific ready condition.
Does Puppeteer’s default PDF behavior include page backgrounds?
No. The PDFOptions reference lists printBackground as false by default; set it to true when background graphics are needed.
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