microsoft/markitdown · error · MissingDependencyException

{converter} recognized the input as a potential {extension}

Error message

{converter} recognized the input as a potential {extension} file, but the dependencies needed to read {extension} files have not been installed. To resolve this error, include the optional dependency [{feature}] or [all] when installing MarkItDown. For example:

* pip install 'markitdown[{feature}]'
* pip install 'markitdown[all]'
* pip install 'markitdown[{feature}, ...]'
* etc.

What it means

MarkItDown's PptxConverter raises MissingDependencyException when convert() runs but python-pptx (the [pptx] extra) failed to import at module load. accepts() matched .pptx extension or the pptx mimetype, then the dependency guard in convert() fires. The pattern is identical to the other office converters: import failure is cached in _dependency_exc_info at module import time and re-raised here with formatting instructions.

Source

Thrown at packages/markitdown/src/markitdown/converters/_pptx_converter.py:69

        if extension in ACCEPTED_FILE_EXTENSIONS:
            return True

        for prefix in ACCEPTED_MIME_TYPE_PREFIXES:
            if mimetype.startswith(prefix):
                return True

        return False

    def convert(
        self,
        file_stream: BinaryIO,
        stream_info: StreamInfo,
        **kwargs: Any,  # Options to pass to the converter
    ) -> DocumentConverterResult:
        # Check the dependencies
        if _dependency_exc_info is not None:
            raise MissingDependencyException(
                MISSING_DEPENDENCY_MESSAGE.format(
                    converter=type(self).__name__,
                    extension=".pptx",
                    feature="pptx",
                )
            ) from _dependency_exc_info[
                1
            ].with_traceback(  # type: ignore[union-attr]
                _dependency_exc_info[2]
            )

        # Perform the conversion
        presentation = pptx.Presentation(file_stream)
        md_content = ""
        slide_num = 0
        for slide in presentation.slides:
            slide_num += 1

View on GitHub (pinned to fd239d5d2b)

Solutions

  1. Install the pptx extra: pip install 'markitdown[pptx]'
  2. Or: pip install 'markitdown[all]'
  3. Test the underlying import: python -c "import pptx"; if it fails on lxml, align the lxml version (pip install -U lxml)
  4. Pin markitdown[all] in deployment manifests to avoid per-format extras being forgotten

Example fix

# before
pip install markitdown
MarkItDown().convert("deck.pptx")  # MissingDependencyException

# after
pip install 'markitdown[pptx]'
MarkItDown().convert("deck.pptx")
Defensive patterns

Strategy: try-catch

Validate before calling

from markitdown.converters._pptx_converter import _dependency_exc_info

def can_convert_pptx() -> bool:
    return _dependency_exc_info is None

Try / catch

from markitdown import MarkItDown, MissingDependencyException

try:
    result = MarkItDown().convert("deck.pptx")
except MissingDependencyException:
    logger.error("install markitdown[pptx] to process PowerPoint files")
    raise

Prevention

When it happens

Trigger: Calling convert() on a stream with extension .pptx or mimetype application/vnd.openxmlformats-officedocument.presentationml.presentation when markitdown lacks the [pptx] extra, or when python-pptx imports fail (lxml incompatibility is the classic cause).

Common situations: Slide-deck ingestion services built on base markitdown; lxml version pins from other packages breaking python-pptx's import; Docker images cached from before the extras were added to the project.

Related errors

AI-assisted analysis of microsoft/markitdown@fd239d5d2b (2026-08-14). Data as JSON: /api/errors/b749f6c865ff5006. Report an issue: GitHub.