With sentence_transformers>=4, SetFit throws TypeError: on_init_end() missing 1 required positional argument: 'trainer'

[amaiya]

In sentence_transformers>=4.0, which was released on March 26th, SetFit throws a type error:

Traceback (most recent call last):
  File "/home/user/projects/ghub/onprem/nbs/tests/test_onprem.py", line 699, in <module>
    run(**kwargs)
  File "/home/user/projects/ghub/onprem/nbs/tests/test_onprem.py", line 639, in run
    fn(**kwargs)
  File "/home/user/projects/ghub/onprem/nbs/tests/test_onprem.py", line 291, in test_classifier
    clf.train(X_sample,  y_sample, max_steps=1)
  File "/home/user/projects/ghub/onprem/onprem/pipelines/classifier.py", line 494, in train
    trainer = Trainer(
  File "/home/user/mambaforge/lib/python3.9/site-packages/setfit/trainer.py", line 335, in __init__
    self.st_trainer = BCSentenceTransformersTrainer(
  File "/home/user/mambaforge/lib/python3.9/site-packages/setfit/trainer.py", line 101, in __init__
    self.callback_handler.on_init_end(self.args, self.state, self.control)
  File "/home/user/mambaforge/lib/python3.9/site-packages/transformers/trainer_callback.py", line 503, in on_init_end
    return self.call_event("on_init_end", args, state, control)
  File "/home/user/mambaforge/lib/python3.9/site-packages/setfit/trainer.py", line 94, in <lambda>
    self.callback_handler.call_event = lambda *args, **kwargs: overwritten_call_event(
  File "/home/user/mambaforge/lib/python3.9/site-packages/setfit/trainer.py", line 71, in overwritten_call_event
    result = getattr(callback, event)(
TypeError: on_init_end() missing 1 required positional argument: 'trainer'  

[firmai]

Setfit has always been unstable, good luck for figuring it out. I would avoid using it in production.

[alashti]

Hi,

I have also faced this error even when trying to run the example provided in the readme or the huggingface example.
I tried different versions of Transformers and setfit. And I also tried to create a custom callback or disable it. but none worked.

[tomaarsen]

Sentence Transformers<3.4.0 should work, and otherwise I've got a fix in #595. I'll get that released soon.

• Tom Aarsen