affaan-m/ECC · error · RuntimeError

could not set for

Error message

could not set {key} for {event['id']}

What it means

After appending, apply_placements sets each item's Opacity and CompositeMode via item.SetProperty and raises this RuntimeError if SetProperty returns a falsy value (Resolve returns False when the property name or value is rejected). The message names the property key and event id. This ensures each overlay's compositing matches the plan before readback verification.

Solutions

1. Ensure opacity is a number in 0-100 and composite is an integer in Resolve's accepted CompositeMode range.
2. Test item.SetProperty('CompositeMode', v) manually in the Resolve console for your build to confirm supported values.
3. Upgrade/downgrade or adjust the plan to composite modes supported by the running Resolve version.

Example fix

// before
event["composite"] = "overlay"
// after
event["composite"] = 1  # Resolve CompositeMode integer

for e in plan:
    if not isinstance(e["opacity"], (int, float)) or not 0 <= e["opacity"] <= 100:
        raise ValueError(f"bad opacity for {e['id']}")
    if not isinstance(e["composite"], int) or not 0 <= e["composite"] <= 100:
        raise ValueError(f"bad composite mode for {e['id']}")

def valid_properties(event):
    return (
        isinstance(event.get("opacity"), (int, float))
        and 0 <= event["opacity"] <= 100
        and isinstance(event.get("composite"), int)
        and 0 <= event["composite"] <= 100
    )

try:
    apply_placements(tl, pool, placements, ...)
except RuntimeError as e:
    if "could not set" in str(e):
        key, eid = str(e).split()[3], str(e).split()[5]
        print(f"property {key} rejected for {eid}; check Resolve-accepted values")
    else:
        raise

When it happens

Trigger: Passing a CompositeMode value outside Resolve's accepted set (0-100 integer enum, e.g. 'overlay' string or 7 when unsupported), passing Opacity as a string or out of 0-100, or a Resolve build silently failing SetProperty on a freshly appended item.

Common situations: Plan JSON with composite modes copied from another tool's naming; opacity given as '50' (string) instead of 50.0; Resolve version where a composite mode enum was added/removed.

Understand the failure class

Background: "Must be a positive integer", "Invalid value", "Unsupported": the invalid-argument-value error family, when a library rejects the value you pass — this error's family across 35 libraries.

Related errors

• could not append
• could not create overlay track
• could not import
• unexpected overlay items after append
• base_track_count exceeds target video tracks

AI-assisted analysis of affaan-m/ECC@8321021c54 (2026-09-16). Data as JSON: /api/errors/25c548bdd74e6904. Report an issue: GitHub.

Appendix: source

Thrown at skills/taste-application/scripts/tasteforge/resolve.py:301

                {
                    "mediaPoolItem": imported[0],
                    "startFrame": 0,
                    "endFrame": event["frames"] - (source_end_mode == "inclusive"),
                    "mediaType": 1,
                    "trackIndex": event["track"],
                    "recordFrame": event["record_frame"],
                }
            ]
        )
        if not items or len(items) != 1:
            raise RuntimeError(f"could not append {event['id']}")
        item = items[0]
        for key, value in [
            ("Opacity", event["opacity"]),
            ("CompositeMode", event["composite"]),
        ]:
            if not item.SetProperty(key, value):
                raise RuntimeError(f"could not set {key} for {event['id']}")
        _readback(timeline, item, event)
        appended.append((event, item))
    receipts = []
    for event, item in appended:
        actual = _readback(timeline, item, event)
        receipts.append(
            {
                "id": event["id"],
                "asset": event["asset"],
                "requested": {
                    key: event[key]
                    for key in (
                        "record_frame",
                        "frames",
                        "track",
                        "opacity",
                        "composite",
                    )

View on GitHub (pinned to 8321021c54)