ytdl-org/youtube-dl · error · ExtractorError

Class %r not found

Error message

Class %r not found

What it means

Error "Class %r not found" thrown in ytdl-org/youtube-dl.

Source

Thrown at youtube_dl/swfinterp.py:428

                u30()  # from
                u30()  # to
                u30()  # target
                u30()  # exc_type
                u30()  # var_name
            trait_count = u30()
            for _c2 in range(trait_count):
                parse_traits_info()

        assert p + code_reader.tell() == len(code_tag)

    def patch_function(self, avm_class, func_name, f):
        self._patched_functions[(avm_class, func_name)] = f

    def extract_class(self, class_name, call_cinit=True):
        try:
            res = self._classes_by_name[class_name]
        except KeyError:
            raise ExtractorError('Class %r not found' % class_name)

        if call_cinit and hasattr(res, 'cinit_idx'):
            res.register_methods({'$cinit': res.cinit_idx})
            res.methods['$cinit'] = self._all_methods[res.cinit_idx]
            cinit = self.extract_function(res, '$cinit')
            cinit([])

        return res

    def extract_function(self, avm_class, func_name):
        p = self._patched_functions.get((avm_class, func_name))
        if p:
            return p
        if func_name in avm_class.method_pyfunctions:
            return avm_class.method_pyfunctions[func_name]
        if func_name in self._classes_by_name:
            return self._classes_by_name[func_name].make_object()
        if func_name not in avm_class.methods:

View on GitHub (pinned to 956b8c5855)

Solutions

1. Update youtube-dl; the SWF references a class the interpreter cannot find.

When it happens

Trigger: Thrown at youtube_dl/swfinterp.py:428 when the library encounters an invalid state.

Common situations: See trigger scenarios.

AI-assisted analysis of ytdl-org/youtube-dl@956b8c5855 (2026-08-14). Data as JSON: /api/errors/f269977cf9450896. Report an issue: GitHub.