Comfy-Org/ComfyUI · error · ValueError

Unknown fuse_method '{fuse_method}'.

Error message

Unknown fuse_method '{fuse_method}'.

What it means

get_matching_fuse_method resolves a fusion-strategy name to a weight function via FUSE_MAPPING (FLAT, PYRAMID, RELATIVE, OVERL_LINEAR). Unknown names raise ValueError. Note RELATIVE maps to the same pyramid weight function as PYRAMID — only these four identifiers are legal.

Source

Thrown at comfy/context_windows.py:988

    PYRAMID = "pyramid"
    RELATIVE = "relative"
    OVERLAP_LINEAR = "overlap-linear"

    LIST = [PYRAMID, FLAT, OVERLAP_LINEAR]
    LIST_STATIC = [PYRAMID, RELATIVE, FLAT, OVERLAP_LINEAR]


FUSE_MAPPING = {
    ContextFuseMethods.FLAT: create_weights_flat,
    ContextFuseMethods.PYRAMID: create_weights_pyramid,
    ContextFuseMethods.RELATIVE: create_weights_pyramid,
    ContextFuseMethods.OVERLAP_LINEAR: create_weights_overlap_linear,
}

def get_matching_fuse_method(fuse_method: str) -> ContextFuseMethod:
    func = FUSE_MAPPING.get(fuse_method, None)
    if func is None:
        raise ValueError(f"Unknown fuse_method '{fuse_method}'.")
    return ContextFuseMethod(fuse_method, func)

# Returns fraction that has denominator that is a power of 2
def ordered_halving(val):
    # get binary value, padded with 0s for 64 bits
    bin_str = f"{val:064b}"
    # flip binary value, padding included
    bin_flip = bin_str[::-1]
    # convert binary to int
    as_int = int(bin_flip, 2)
    # divide by 1 << 64, equivalent to 2**64, or 18446744073709551616,
    # or b10000000000000000000000000000000000000000000000000000000000000000 (1 with 64 zero's)
    return as_int / (1 << 64)


def get_missing_indexes(windows: list[list[int]], num_frames: int) -> list[int]:
    all_indexes = list(range(num_frames))
    for w in windows:

View on GitHub (pinned to 1c6d8d45b3)

Solutions

1. Pass one of the exact identifiers: see ContextFuseMethods in comfy/context_windows.py (e.g. 'flat', 'pyramid', 'relative', 'overlap_linear' — use the enum to avoid spelling issues).
2. Restrict node inputs to a combo built from list(FUSE_MAPPING).
3. Map external names to supported ones before calling (gaussian→pyramid if acceptable).

Example fix

# before
get_matching_fuse_method("overlap-linear")

# after
from comfy.context_windows import ContextFuseMethods, get_matching_fuse_method
get_matching_fuse_method(ContextFuseMethods.OVERLAP_LINEAR)

from comfy.context_windows import FUSE_MAPPING
if fuse_method not in FUSE_MAPPING:
    raise SystemExit(f"unknown fuse method; valid: {list(FUSE_MAPPING)}")
fuse = get_matching_fuse_method(fuse_method)

from comfy.context_windows import FUSE_MAPPING
def is_valid_fuse_method(name: str) -> bool:
    return name in FUSE_MAPPING

try:
    fuse = get_matching_fuse_method(name)
except ValueError:
    fuse = get_matching_fuse_method("flat")  # safe default

When it happens

Trigger: Calling get_matching_fuse_method with a misspelled or newer fuse name ('pyrmaid', 'gaussian', 'overlap-linear' with a dash instead of underscore); custom nodes exposing their own fuse names not present in FUSE_MAPPING.

Common situations: Free-text input fields instead of combos; enum drift between ComfyUI versions; copy-pasting fuse method names from other tools (AnimateDiff 'gaussian' etc.).

Related errors

• Unknown context_schedule '{context_schedule}'.
• {cls.__name__} does not have a NONE member to map None to
• Invalid {cls.__name__} string: '{value}'. Valid values are:
• Cannot convert type {type(value).__name__} to {cls.__name__}
• Invalid causality_axis: {causality_axis}

AI-assisted analysis of Comfy-Org/ComfyUI@1c6d8d45b3 (2026-08-14). Data as JSON: /api/errors/da912772ca8ae570. Report an issue: GitHub.