Let's work through the possible issues and fixes for your scenario—using 32-bit wkhtmltopdf 0.12.4 on Windows Server 2016, where your generated PDF only shows blue boxes instead of the expected images from the target webpage:

1. Check Image Loading Permissions & Cross-Domain Restrictions #

• Cross-domain or authenticated images: wkhtmltopdf's default security settings might block images from external domains or those requiring authentication. Try adding --disable-web-security (use cautiously in production environments) or --enable-external-links to loosen these restrictions.
• Server network access: Windows Server 2016 may have firewalls, proxies, or group policies blocking the wkhtmltopdf process from fetching external images. First, manually load the target webpage on the server to confirm images display correctly, then verify the account running wkhtmltopdf has proper network access rights.

2. Tweak JavaScript Rendering Parameters #

You already added --javascript-delay 3000, but let's adjust further to account for slower dynamic loading:

• Extend delay time: Bump --javascript-delay to 5000 or 10000—some dynamically loaded images need extra time to initialize and fully load.
• Explicitly enable JavaScript: Add --enable-javascript (even though 0.12.4 enables it by default, explicit setting avoids potential config quirks that might disable it).
• Disable caching: Include --no-cache to rule out stale cached resources interfering with fresh image rendering.

3. Address Architecture & Version Compatibility #

Running a 32-bit tool on a 64-bit OS can introduce compatibility gaps:

• Switch to 64-bit wkhtmltopdf 0.12.4: 32-bit processes on 64-bit systems may hit resource limits or have rendering engine bugs that break image loading.
• Upgrade to a newer stable version: Consider moving to wkhtmltopdf 0.12.6 (the latest stable release as of now). Older versions like 0.12.4 have known gaps in supporting modern JavaScript-driven image loading workflows.

4. Inspect Webpage Print Styles #

Some webpages use @media print CSS to modify content for printing, which might intentionally hide images or replace them with placeholder boxes:

• Check the page's print styles for rules like display: none or visibility: hidden targeting image elements, or styles that use background color boxes instead of actual images.
• Test with --print-media-type (forces print-style rendering) or --no-print-media-type (uses screen-style rendering) to see if either resolves the issue.

5. Debug the Rendering Process #

• Add --debug-javascript to output JavaScript execution logs—this can reveal script errors that prevent images from loading properly.
• Use --dump-dom to save the rendered DOM to a file, then check if image elements have valid src attributes or if there are error messages embedded in the DOM.

Here's a modified command incorporating these suggestions:

wkhtmltopdf.exe --enable-javascript --no-stop-slow-scripts --javascript-delay 10000 --disable-web-security --no-print-media-type -O landscape https://stage-plan.com/stageplan/plan/bccfbd53-8b89-4401-b08a-95ea8af57361#hideScrollDownMessage c:\page.pdf

内容的提问来源于stack exchange，提问作者MyDaftQuestions