hpcaitech/Open-Sora · error · ValueError

upsample factor {factor} is not supported for decoder projec

Error message

upsample factor {factor} is not supported for decoder project out

What it means

build_decoder_project_out_block only supports project_out factors 1 and 2; any other factor value raises this ValueError when the decoder is constructed.

Source

Thrown at opensora/models/dc_ae/models/dc_ae.py:372

                out_channels=out_channels,
                kernel_size=3,
                stride=1,
                use_bias=True,
                norm=None,
                act_func=None,
                is_video=is_video,
            )
        )
    elif factor == 2:
        if is_video:
            raise NotImplementedError("Upsample during project_out is not supported for video")
        layers.append(
            build_upsample_block(
                block_type=upsample_block_type, in_channels=in_channels, out_channels=out_channels, shortcut=None
            )
        )
    else:
        raise ValueError(f"upsample factor {factor} is not supported for decoder project out")
    return OpSequential(layers)


class Encoder(nn.Module):
    def __init__(self, cfg: EncoderConfig):
        super().__init__()
        self.cfg = cfg
        num_stages = len(cfg.width_list)
        self.num_stages = num_stages
        assert len(cfg.depth_list) == num_stages
        assert len(cfg.width_list) == num_stages
        assert isinstance(cfg.block_type, str) or (
            isinstance(cfg.block_type, list) and len(cfg.block_type) == num_stages
        )

        self.project_in = build_encoder_project_in_block(
            in_channels=cfg.in_channels,
            out_channels=cfg.width_list[0] if cfg.depth_list[0] > 0 else cfg.width_list[1],

View on GitHub (pinned to 7ad6a96a13)

Solutions

Set project_out_factor to 1 or 2
Use a shipped config for the target checkpoint
Patch build_decoder_project_out_block locally if a new factor is genuinely required

Example fix

# before
project_out_factor: 4
# after
project_out_factor: 2

Defensive patterns

Strategy: validation

Validate before calling

assert project_out_factor in (1, 2), f'unsupported project_out factor: {project_out_factor}'

Prevention

Whitelist factor values at config load
Validate decoder config schema before init

When it happens

Trigger: Setting project_out_factor to 4, 8, or any value besides 1/2 in the DCAE decoder config.

Common situations: Attempting to match a different latent-compression scheme by editing the factor; config drift between opensora versions.

Understand the failure class

Background: "Invalid value" and "allowed values are" config errors: what your library rejected and how to fix it — this error's family across 41 libraries.

Related errors

AI-assisted analysis of hpcaitech/Open-Sora@7ad6a96a13 (2026-08-28). Data as JSON: /api/errors/024452bf42c42507. Report an issue: GitHub.