From 9060b45465157e7997cabff50b2488e2fc2d5973 Mon Sep 17 00:00:00 2001
From: venti <1308199824@qq.com>
Date: Sat, 30 May 2026 16:42:08 +0800
Subject: [PATCH] fix: guard against missing oMath element in DOCX math
 converter (#1979)

Add a None check in _convert_omath_to_latex() to return an empty
string when the math element is missing, instead of passing None to
oMath2Latex() which raises TypeError.

Fixes #1979
---
 .../converter_utils/docx/pre_process.py       |  2 +
 packages/markitdown/tests/test_module_misc.py | 63 +++++++++++++++++++
 2 files changed, 65 insertions(+)

diff --git a/packages/markitdown/src/markitdown/converter_utils/docx/pre_process.py b/packages/markitdown/src/markitdown/converter_utils/docx/pre_process.py
index d6fa8db69..257f0387f 100644
--- a/packages/markitdown/src/markitdown/converter_utils/docx/pre_process.py
+++ b/packages/markitdown/src/markitdown/converter_utils/docx/pre_process.py
@@ -44,6 +44,8 @@ def _convert_omath_to_latex(tag: Tag) -> str:
     math_root = ET.fromstring(MATH_ROOT_TEMPLATE.format(str(tag)))
     # Find the 'oMath' element within the XML document
     math_element = math_root.find(OMML_NS + "oMath")
+    if math_element is None:
+        return ""
     # Convert the 'oMath' element to LaTeX using the oMath2Latex function
     latex = oMath2Latex(math_element).latex
     return latex
diff --git a/packages/markitdown/tests/test_module_misc.py b/packages/markitdown/tests/test_module_misc.py
index 4d62e4919..bce508790 100644
--- a/packages/markitdown/tests/test_module_misc.py
+++ b/packages/markitdown/tests/test_module_misc.py
@@ -274,6 +274,69 @@ def test_docx_equations() -> None:
     assert block_equations, "No block equations found in the document."
 
 
+def test_docx_malformed_equations() -> None:
+    """Malformed equations should not crash the converter (issue #1979)."""
+    import zipfile
+    from io import BytesIO
+
+    docx_xml = """<?xml version="1.0" encoding="UTF-8" standalone="yes"?>
+<w:document xmlns:m="http://schemas.openxmlformats.org/officeDocument/2006/math"
+            xmlns:w="http://schemas.openxmlformats.org/wordprocessingml/2006/main"
+            xmlns:mc="http://schemas.openxmlformats.org/markup-compatibility/2006"
+            mc:Ignorable="w14 wp14">
+  <w:body>
+    <w:p>
+      <w:r><w:t>Normal text</w:t></w:r>
+    </w:p>
+    <m:oMathPara>
+      <m:oMath>
+        <m:r><m:t>x+1</m:t></m:r>
+      </m:oMath>
+    </m:oMathPara>
+    <w:p>
+      <w:r><w:t>After good equation</w:t></w:r>
+    </w:p>
+    <m:oMathPara>
+      <!-- oMathPara with no oMath child -->
+    </m:oMathPara>
+    <w:p>
+      <w:r><w:t>After empty oMathPara</w:t></w:r>
+    </w:p>
+    <m:oMath>
+      <!-- empty inline oMath -->
+    </m:oMath>
+    <w:p>
+      <w:r><w:t>After empty inline oMath</w:t></w:r>
+    </w:p>
+  </w:body>
+</w:document>"""
+
+    buf = BytesIO()
+    with zipfile.ZipFile(buf, "w") as z:
+        z.writestr("word/document.xml", docx_xml.encode("utf-8"))
+        z.writestr("[Content_Types].xml", """<?xml version="1.0" encoding="UTF-8" standalone="yes"?>
+<Types xmlns="http://schemas.openxmlformats.org/package/2006/content-types">
+  <Default Extension="rels" ContentType="application/vnd.openxmlformats-package.relationships+xml"/>
+  <Default Extension="xml" ContentType="application/xml"/>
+  <Override PartName="/word/document.xml" ContentType="application/vnd.openxmlformats-officedocument.wordprocessingml.document.main+xml"/>
+</Types>""")
+        z.writestr("word/_rels/document.xml.rels", """<?xml version="1.0" encoding="UTF-8" standalone="yes"?>
+<Relationships xmlns="http://schemas.openxmlformats.org/package/2006/relationships">
+</Relationships>""")
+        z.writestr("_rels/.rels", """<?xml version="1.0" encoding="UTF-8" standalone="yes"?>
+<Relationships xmlns="http://schemas.openxmlformats.org/package/2006/relationships">
+  <Relationship Id="rId1" Type="http://schemas.openxmlformats.org/officeDocument/2006/relationships/officeDocument" Target="word/document.xml"/>
+</Relationships>""")
+
+    buf.seek(0)
+    markitdown = MarkItDown()
+    result = markitdown.convert(buf)
+    assert "Normal text" in result.text_content
+    assert "$x+1$" in result.text_content or "$$x+1$$" in result.text_content
+    assert "After empty oMathPara" in result.text_content
+    assert "After empty inline oMath" in result.text_content
+
+
 def test_input_as_strings() -> None:
     markitdown = MarkItDown()