docling-project/docling · error · ImportError

The 'pylatexenc' package is required to process LaTeX files.

Error message

The 'pylatexenc' package is required to process LaTeX files. Install it with `pip install 'docling-slim[format-latex]'`.

What it means

LatexDocumentBackend.__init__ raises ImportError before super().__init__() when pylatexenc is not installed, chaining the original import error. LaTeX support is an optional extra in docling-slim; the message names the exact extra to install.

Source

Thrown at docling/backend/latex/backend.py:66

    from docling.backend.latex.engines.tectonic import TectonicEngine


class LatexDocumentBackend(
    DeclarativeDocumentBackend,
    MacroHandlerMixin,
    EnvironmentHandlerMixin,
    MathHandlerMixin,
    TextHelperMixin,
    TableHelperMixin,
):
    def __init__(
        self,
        in_doc: InputDocument,
        path_or_stream: Union[BytesIO, Path],
        options: Optional[LatexBackendOptions] = None,
    ):
        if not _PYLATEXENC_AVAILABLE:
            raise ImportError(_INSTALL_HINT) from _PYLATEXENC_IMPORT_ERROR
        if options is None:
            options = LatexBackendOptions()
        super().__init__(in_doc, path_or_stream, options)
        self.options = LatexBackendOptions.model_validate(self.options)
        self.labels: dict[str, bool] = {}
        self._custom_macros: dict[str, str] = {}
        self._custom_macro_num_args: dict[str, int] = {}
        self._input_stack: set[str] = set()
        self._tectonic_engine: TectonicEngine | None = None
        self._tikz_executor: concurrent.futures.ThreadPoolExecutor | None = None
        self._tikz_futures: list[concurrent.futures.Future] = []
        self.latex_text = decode_latex_content(self.path_or_stream)

    def is_valid(self) -> bool:
        text = self.latex_text.strip()
        if not text:
            return False
        return True

View on GitHub (pinned to 61d76f1ff3)

Solutions

1. Install the extra: pip install 'docling-slim[format-latex]'
2. Or install full docling
3. Add the extra to the deployment's dependency manifest so rebuilds keep it

Example fix

# before
pip install docling-slim

# after
pip install 'docling-slim[format-latex]'

try:
    import pylatexenc  # noqa: F401
except ImportError:
    raise RuntimeError("Install: pip install 'docling-slim[format-latex]'")

try:
    result = converter.convert(src)
except ImportError as exc:
    if 'pylatexenc' in str(exc):
        install_or_skip('docling-slim[format-latex]')
    raise

When it happens

Trigger: Converting .tex files (InputFormat.LATEX) in an environment where docling-slim was installed without the format-latex extra, so `import pylatexenc` fails.

Common situations: Minimal deployment images; adding LaTeX conversion to an existing slim-based service without updating dependencies; lockfiles regenerated without the extra.

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AI-assisted analysis of docling-project/docling@61d76f1ff3 (2026-08-14). Data as JSON: /api/errors/f3ee97c5597b7fab. Report an issue: GitHub.