Model loading is broken with transformers >= 5

[vladvrabie-murmuras]

Issue

Running this code with the newer versions of transformers v5.x

import rerankers
rerankers.Reranker("colbert")

throws the following error: AttributeError: 'ColBERTModel' object has no attribute 'all_tied_weights_keys'.
(See full stack trace bellow)

Setup for reproduction:

# mkdir test-issue; cd test-issue
uv init
uv add rerankers[transformers]
uv sync
# Add the above code in main.py
uv run main.py

This installs the newest version of transformers (currently 5.1.0).
See here:

rerankers/pyproject.toml

Line 67 in 5b9cbb0

transformers = ["transformers>=4.45.0", "torch", "sentencepiece", "protobuf"]

The error occurs with both transformers v5.0 and v5.1

Expected behavior

To load and use the model as usual.

Cause

As far as I can tell, transformers v5.x has this PreTrainedModel.post_init() method that they now expect to be called in the __init__() method of derived classes. This method creates the all_tied_weights_keys attribute from the error.
See here: https://github.com/huggingface/transformers/blob/f73a4db3a0bcf6523e9bfdaaf4afe81dffba4da8/src/transformers/modeling_utils.py#L1298

I've seen other people submitting issues for this problem:

• AttributeError: 'MolmoForCausalLM' object has no attribute 'all_tied_weights_keys' huggingface/transformers#43883
• Question about tie_weights huggingface/transformers#42832

Here is the comment in which one of maintainers explains the problem and mentions their expectations: huggingface/transformers#43883 (comment)

Currently, transformers version v4.57 does not raise this error. (I guess any (recent) version <5 works)

For reference, here is the post_init() method from transformers v4.57.6: https://github.com/huggingface/transformers/blob/753d61104116eefc8ffc977327b441ee0c8d599f/src/transformers/modeling_utils.py#L2103

Stack trace

Loading default colbert model for language en
Default Model: colbert-ir/colbertv2.0
Loading ColBERTRanker model colbert-ir/colbertv2.0 (this message can be suppressed by setting verbose=0)
No device set
Using device cpu
No dtype set
Using dtype torch.float32
Loading model colbert-ir/colbertv2.0, this might take a while...
Linear Dim set to: 128 for downcasting
Loading weights: 100%|███████████████████████████████████████████████████████████████████████| 200/200 [00:00<00:00, 2974.21it/s, Materializing param=linear.weight]
ColBERTModel LOAD REPORT from: colbert-ir/colbertv2.0
Key                          | Status     |  |
-----------------------------+------------+--+-
bert.embeddings.position_ids | UNEXPECTED |  |

Notes:
- UNEXPECTED    :can be ignored when loading from different task/architecture; not ok if you expect identical arch.
Traceback (most recent call last):
  File "/home/vlad/Work/test/main.py", line 10, in <module>
    main()
    ~~~~^^
  File "/home/vlad/Work/test/main.py", line 6, in main
    rerankers.Reranker("colbert")
    ~~~~~~~~~~~~~~~~~~^^^^^^^^^^^
  File "/home/vlad/Work/test/.venv/lib/python3.13/site-packages/rerankers/reranker.py", line 238, in Reranker
    return AVAILABLE_RANKERS[model_type](model_name, verbose=verbose, **kwargs)
           ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
  File "/home/vlad/Work/test/.venv/lib/python3.13/site-packages/rerankers/models/colbert_ranker.py", line 238, in __init__
    ColBERTModel.from_pretrained(
    ~~~~~~~~~~~~~~~~~~~~~~~~~~~~^
        model_name,
        ^^^^^^^^^^^
        verbose=self.verbose,
        ^^^^^^^^^^^^^^^^^^^^^
        **model_kwargs
        ^^^^^^^^^^^^^^
    )
    ^
  File "/home/vlad/Work/test/.venv/lib/python3.13/site-packages/transformers/modeling_utils.py", line 4064, in from_pretrained
    loading_info = cls._finalize_model_loading(model, load_config, loading_info)
  File "/home/vlad/Work/test/.venv/lib/python3.13/site-packages/transformers/modeling_utils.py", line 4205, in _finalize_model_loading
    model.mark_tied_weights_as_initialized()
    ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~^^
  File "/home/vlad/Work/test/.venv/lib/python3.13/site-packages/transformers/modeling_utils.py", line 4524, in mark_tied_weights_as_initialized
    for tied_param in self.all_tied_weights_keys.keys():
                      ^^^^^^^^^^^^^^^^^^^^^^^^^^
  File "/home/vlad/Work/test/.venv/lib/python3.13/site-packages/torch/nn/modules/module.py", line 1965, in __getattr__
    raise AttributeError(
        f"'{type(self).__name__}' object has no attribute '{name}'"
    )
AttributeError: 'ColBERTModel' object has no attribute 'all_tied_weights_keys'. Did you mean: '_tied_weights_keys'?