Accessing PdfReader.outline causes "AssertionError: mypy"

[AbdiHaryadi]

I was attempting to read the outline of a PDF (link here), but I found an unexpected AssertionError.

Environment

My environment was in Google Colab with a simple PIP installation setup.

!pip install pypdf

Here is the debug:

$ python -m platform
Linux-6.1.123+-x86_64-with-glibc2.35

$ python -c "import pypdf;print(pypdf._debug_versions)"
pypdf==6.0.0, crypt_provider=('cryptography', '43.0.3'), PIL=11.3.0

Code + PDF

This is a minimal, complete example that shows the issue:

from pypdf import PdfReader

pdf_reader = PdfReader("e371fffe0b_a7cccde95a.pdf")
outline = pdf_reader.outline

Download the PDF file here (14 MB). Sorry, it's not a small PDF.

Traceback

This is the complete traceback I see:

---------------------------------------------------------------------------

AssertionError                            Traceback (most recent call last)

[/tmp/ipython-input-381717387.py](https://localhost:8080/#) in <cell line: 0>()
      1 from pypdf import PdfReader
      2 pdf_reader = PdfReader("e371fffe0b_a7cccde95a.pdf")
----> 3 outline = pdf_reader.outline

6 frames

[/usr/local/lib/python3.12/dist-packages/pypdf/_doc_common.py](https://localhost:8080/#) in outline(self)
    830         'bookmarks').
    831         """
--> 832         return self._get_outline()
    833 
    834     def _get_outline(

[/usr/local/lib/python3.12/dist-packages/pypdf/_doc_common.py](https://localhost:8080/#) in _get_outline(self, node, outline)
    849                 if not is_null_or_none(lines) and "/First" in lines:
    850                     node = cast(DictionaryObject, lines["/First"])
--> 851             self._named_destinations = self._get_named_destinations()
    852 
    853         if node is None:

[/usr/local/lib/python3.12/dist-packages/pypdf/_doc_common.py](https://localhost:8080/#) in _get_named_destinations(self, tree, retval)
    480             # recurse down the tree
    481             for kid in cast(ArrayObject, tree[PagesAttributes.KIDS]):
--> 482                 self._get_named_destinations(kid.get_object(), retval)
    483         # §7.9.6, entries in a name tree node dictionary
    484         elif CA.NAMES in tree:  # /Kids and /Names are exclusives (§7.9.6)

[/usr/local/lib/python3.12/dist-packages/pypdf/_doc_common.py](https://localhost:8080/#) in _get_named_destinations(self, tree, retval)
    501                     else:
    502                         continue
--> 503                 dest = self._build_destination(key, value)
    504                 if dest is not None:
    505                     retval[key] = dest

[/usr/local/lib/python3.12/dist-packages/pypdf/_doc_common.py](https://localhost:8080/#) in _build_destination(self, title, array)
    947         page, typ, *array = array  # type: ignore
    948         try:
--> 949             return Destination(title, page, Fit(fit_type=typ, fit_args=array))  # type: ignore
    950         except PdfReadError:
    951             logger_warning(f"Unknown destination: {title} {array}", __name__)

[/usr/local/lib/python3.12/dist-packages/pypdf/generic/_data_structures.py](https://localhost:8080/#) in __init__(self, title, page, fit)
   1611 
   1612         DictionaryObject.__init__(self)
-> 1613         self[NameObject("/Title")] = TextStringObject(title)
   1614         self[NameObject("/Page")] = page
   1615         self[NameObject("/Type")] = typ

[/usr/local/lib/python3.12/dist-packages/pypdf/generic/_base.py](https://localhost:8080/#) in __new__(cls, value)
    670         o.utf16_bom = b""
    671         if o.startswith(("\xfe\xff", "\xff\xfe")):
--> 672             assert org is not None, "mypy"
    673             try:
    674                 o = str.__new__(cls, org.decode("utf-16"))

AssertionError: mypy

[stefan6419846]

Thanks for the report. This seems to be a side-effect of the fix in #3259.

[stefan6419846]

Test file: e371fffe0b_a7cccde95a.pdf