infiniflow/ragflow · error · Exception

No PDF engine found. Install xelatex.

Error message

No PDF engine found. Install xelatex.

What it means

Raised by DocGenerator._select_pdf_engine (agent/component/docs_generator.py): the component requires xelatex to produce PDF output (needed for CJK font support via -V mainfont/CJKmainfont args), and shutil.which('xelatex') found no xelatex binary on PATH. This is an environment dependency error, not a configuration error.

Source

Thrown at agent/component/docs_generator.py:281

        include_timestamp_in_body: bool = True,
    ) -> tuple[str, bytes]:
        import pypandoc

        markdown_content = self._build_markdown_source(
            content,
            include_timestamp_in_body=include_timestamp_in_body,
        )
        converted_content = pypandoc.convert_text(
            markdown_content,
            to=target_format,
            format="markdown",
        )
        return self._write_bytes_output(converted_content.encode("utf-8"), extension)

    def _select_pdf_engine(self) -> str:
        if shutil.which("xelatex"):
            return "xelatex"
        raise Exception("No PDF engine found. Install xelatex.")

    def _get_pdf_font_args(self) -> list[str]:
        return [
            "-V",
            f"mainfont={self._pdf_main_font}",
            "-V",
            f"CJKmainfont={self._pdf_cjk_font}",
        ]

    def _get_pdf_overlay_font_name(self) -> str:
        from reportlab.pdfbase import pdfmetrics
        from reportlab.pdfbase.cidfonts import UnicodeCIDFont

        try:
            pdfmetrics.getFont(self._pdf_overlay_font)
        except KeyError:
            pdfmetrics.registerFont(UnicodeCIDFont(self._pdf_overlay_font))

View on GitHub (pinned to 554fb1133a)

Solutions

  1. Install TeX Live with xelatex: on Debian/Ubuntu 'apt-get install -y texlive-xetex' (plus texlive-fonts-recommended for Noto/STSong fonts)
  2. In Docker, add the same packages to the image and rebuild so xelatex is on PATH
  3. Verify with 'which xelatex' / 'xelatex --version' in the exact environment the backend worker runs in
  4. As a workaround, switch output_format to 'docx', 'html', 'txt', or 'markdown', which do not need a TeX engine

Example fix

# before: Dockerfile without TeX
FROM ragflow-base

# after
RUN apt-get update && apt-get install -y --no-install-recommends texlive-xetex texlive-fonts-recommended
Defensive patterns

Strategy: fallback

Validate before calling

import shutil

def pdf_engine_available() -> bool:
    return shutil.which('xelatex') is not None

if not pdf_engine_available():
    raise EnvironmentError('PDF output requires xelatex; install texlive-xetex or choose another output_format')

Try / catch

try:
    path, data = generator._generate_pdf(content)
except Exception as e:
    if 'No PDF engine found' in str(e):
        path, data = generator._generate_docx(content)  # degrade gracefully, notify user
    else:
        raise

Prevention

When it happens

Trigger: Running an agent canvas with a DocGenerator component whose output_format is 'pdf' on a host or container where TeX Live (xelatex) is not installed or not on PATH. The check is unconditional: only xelatex is accepted, then Exception('No PDF engine found. Install xelatex.').

Common situations: Slim Docker images without TeX Live; local venv installs of RAGFlow without system packages; CI runners lacking texlive; PATH not including /usr/local/texlive/*/bin/* after a manual TeX install.

Related errors

AI-assisted analysis of infiniflow/ragflow@554fb1133a (2026-08-15). Data as JSON: /api/errors/3106b388177ec338. Report an issue: GitHub.