sgl-project/sglang · critical · ValueError

{rope_type=} not supported. Choose between 'interleaved' and

Error message

{rope_type=} not supported. Choose between 'interleaved' and 'split'.

What it means

The LTX-2 rotary module supports exactly two layouts: 'interleaved' (pairs at stride 2) and 'split' (first-half/second-half). Any other rope_type string is rejected at init because the positional-encoding math differs per layout.

Source

Thrown at python/sglang/multimodal_gen/runtime/models/dits/ltx_2.py:401

        base_height: int = 2048,
        base_width: int = 2048,
        sampling_rate: int = 16000,
        hop_length: int = 160,
        scale_factors: Tuple[int, ...] = (8, 32, 32),
        theta: float = 10000.0,
        causal_offset: int = 1,
        modality: str = "video",
        double_precision: bool = True,
        rope_type: str = "interleaved",
        num_attention_heads: int = 32,
    ) -> None:
        super().__init__()
        self.dim = int(dim)
        self.patch_size = int(patch_size)
        self.patch_size_t = int(patch_size_t)

        if rope_type not in ["interleaved", "split"]:
            raise ValueError(
                f"{rope_type=} not supported. Choose between 'interleaved' and 'split'."
            )
        self.rope_type = rope_type

        self.base_num_frames = int(base_num_frames)
        self.num_attention_heads = int(num_attention_heads)

        self.base_height = int(base_height)
        self.base_width = int(base_width)

        self.sampling_rate = int(sampling_rate)
        self.hop_length = int(hop_length)
        self.audio_latents_per_second = (
            float(self.sampling_rate) / float(self.hop_length) / float(scale_factors[0])
        )

        self.scale_factors = tuple(int(x) for x in scale_factors)
        self.theta = float(theta)

View on GitHub (pinned to 0132848349)

Solutions

1. Set rope_type to 'interleaved' or 'split' exactly
2. Match the value used during checkpoint training (wrong layout silently degrades quality even when it loads)
3. Add a config alias mapping if you control the loader

Example fix

// before
rope = LTX2RotaryPosEmbed(..., rope_type="default")

// after
rope = LTX2RotaryPosEmbed(..., rope_type="split")

assert rope_type in ('interleaved', 'split'), f'{rope_type=} unsupported'

def is_supported_rope_type(v: str) -> bool:\n    return v in ('interleaved', 'split')

When it happens

Trigger: Constructing LTX2RotaryPosEmbed with rope_type='concat', 'default', None, or a typo like 'splitt'.

Common situations: Porting config from another DiT whose rope naming differs; hand-written config JSON; case differences ('Split' vs 'split').

Related errors

• Modality {modality} is not supported. Supported modalities a
• Unknown activation function: {act_fn}
• Invalid fused KV rotary/head dim pair: rotary_dim={rotary_di
• Invalid fused KV rotary/head dim pair: rotary_dim={self.rota
• RoPE config mismatch across layers for fused KV path: expect

AI-assisted analysis of sgl-project/sglang@0132848349 (2026-08-28). Data as JSON: /api/errors/5907f767bdfeff4e. Report an issue: GitHub.