huggingface/transformers · error · ValueError

`forced_decoder_ids` is deprecated in favor of `task` and `l

Error message

`forced_decoder_ids` is deprecated in favor of `task` and `language` and, as such, `begin_index` must be provided to `WhisperTimeStampLogitsProcessor`. The previous default value of `begin_index` was `len(generate_config.forced_decoder_ids)`

What it means

Error "`forced_decoder_ids` is deprecated in favor of `task` and `language` and, as such, `begin_index` must be provided to `WhisperTimeStampLogitsProcessor`. The previous default value of `begin_index` was `len(generate_config.forced_decoder_ids)`" thrown in huggingface/transformers.

Source

Thrown at src/transformers/generation/logits_process.py:1986

        self,
        generate_config: "GenerationConfig",
        begin_index: int,
        _detect_timestamp_from_logprob: bool | None = None,
    ):  # support for the kwargs
        whisper_generate_config = cast(WhisperGenerationConfigLike, generate_config)
        self.no_timestamps_token_id = whisper_generate_config.no_timestamps_token_id
        self.timestamp_begin = whisper_generate_config.no_timestamps_token_id + 1
        self.eos_token_id = generate_config.eos_token_id or generate_config.bos_token_id

        # this variable is mostly just used for testing
        self._detect_timestamp_from_logprob = (
            _detect_timestamp_from_logprob
            if _detect_timestamp_from_logprob is not None
            else getattr(generate_config, "_detect_timestamp_from_logprob", True)
        )
        self.begin_index = begin_index
        if begin_index is None:
            raise ValueError(
                "`forced_decoder_ids` is deprecated in favor of `task` and `language` and, as such, `begin_index` "
                "must be provided to `WhisperTimeStampLogitsProcessor`. The previous default value of `begin_index` "
                "was `len(generate_config.forced_decoder_ids)`"
            )

        self.max_initial_timestamp_index = getattr(generate_config, "max_initial_timestamp_index", None)
        # TODO(Patrick): Make sure that official models have max_initial_timestamp_index set to 50
        # self.max_initial_timestamp_index = 50

    def set_begin_index(self, begin_index):
        self.begin_index = begin_index

    @add_start_docstrings(LOGITS_PROCESSOR_INPUTS_DOCSTRING)
    def __call__(self, input_ids: torch.LongTensor, scores: torch.FloatTensor) -> torch.FloatTensor:
        # suppress <|notimestamps|> which is handled by without_timestamps
        scores_processed = scores.clone()
        scores_processed[:, self.no_timestamps_token_id] = -float("inf")

View on GitHub (pinned to a597f97485)

Solutions

1. Provide `begin_index` explicitly to `WhisperTimeStampLogitsProcessor`.
2. Migrate to `task`/`language` generation arguments instead of `forced_decoder_ids`.

When it happens

Trigger: Raised in WhisperTimeStampLogitsProcessor.__init__ when begin_index is not provided because the deprecated forced_decoder_ids path was used.

Common situations: Whisper timestamp generation where begin_index defaults are missing after removing forced_decoder_ids in favor of task/language arguments.

AI-assisted analysis of huggingface/transformers@a597f97485 (2026-08-14). Data as JSON: /api/errors/9733abd276f5446e. Report an issue: GitHub.