Pandoc PDF Error Recovery

Pandoc PDF Error Recovery

Overview

When pandoc fails to convert documents to PDF with an "unknown error" or similar vague message, follow this systematic diagnostic and recovery workflow.

Step-by-Step Procedure

1. Verify Pandoc Installation

First confirm pandoc is installed and accessible:

pandoc --version

If this fails, install pandoc before proceeding:

• macOS: brew install pandoc
• Linux: sudo apt-get install pandoc or sudo yum install pandoc
• Windows: Download from https://pandoc.org/installing.html

2. Check Available PDF Engines

Identify which PDF rendering engines are available on the system:

which pdflatex xelatex lualatex wkhtmltopdf context

Common engines and their typical use cases:

• pdflatex: Standard LaTeX, fast but limited Unicode support
• xelatex: Full Unicode support, recommended for most modern documents
• lualatex: Lua scripting support, good for complex layouts
• wkhtmltopdf: HTML/CSS rendering, good for web-style documents
• context: ConTeXt typesetting system

3. Attempt Conversion with Explicit Engine

Try conversion with xelatex first (most versatile for general documents):

pandoc input.md -o output.pdf --pdf-engine=xelatex 2>&1 | tee conversion.log

The 2>&1 | tee pattern captures both stdout and stderr to a log file for analysis.

4. Analyze Error Output

If conversion fails, examine the captured log:

cat conversion.log

Common error patterns and solutions:

• Missing LaTeX packages: Install with tlmgr install <package> or system package manager
• Font issues: Specify fonts with -V mainfont="Font Name"
• Missing engine: Fall back to available engine (go to Step 5)

5. Try Alternative Engines

Systematically try other available engines:

# Fallback to pdflatex
pandoc input.md -o output.pdf --pdf-engine=pdflatex 2>&1 | tee conversion-pdflatex.log

# Or try wkhtmltopdf for HTML-rich content
pandoc input.md -o output.pdf --pdf-engine=wkhtmltopdf 2>&1 | tee conversion-wkhtmltopdf.log

# Or try lualatex for complex documents
pandoc input.md -o output.pdf --pdf-engine=lualatex 2>&1 | tee conversion-lualatex.log

6. Install Missing Dependencies

If all engines fail or are missing, install required packages:

# Full TeX Live installation (comprehensive but large)
sudo apt-get install texlive-full

# Or minimal installation with common packages
sudo apt-get install texlive-latex-base texlive-fonts-recommended

# For xelatex font support
sudo apt-get install fonts-noto fonts-dejavu

7. Simplify and Retry

If errors persist, try conversion with minimal options:

pandoc input.md -o output.pdf --pdf-engine=xelatex --standalone

Remove complex formatting, custom headers, or advanced LaTeX features that may be causing issues.

Quick Reference Command

Complete diagnostic one-liner:

pandoc --version && which pdflatex xelatex wkhtmltopdf && pandoc input.md -o output.pdf --pdf-engine=xelatex -v

Tips

• Always capture stderr (2>&1) to see the actual error message
• Use -v (verbose) flag for more detailed output during troubleshooting
• For non-English documents, xelatex or lualatex are usually required
• HTML/CSS-heavy documents may work better with wkhtmltopdf
• Check system disk space - PDF generation can require significant temporary space