After Effects Error Asked To Create Unknown Property Of Type Instant

if (layer.hasOwnProperty("sourceRectAtTime")) { // safe to use } When using ExtendScript ( app.project.item(1).layer(1).property.addProperty(...) ), you must use a valid property type string.

Pre‑create the property via a script, or store custom data using text.sourceText on a hidden text layer or marker.comment . 5. Script expecting a specific AE version property Some properties (e.g., 3D Gizmo, Cinema 4D renderer options) exist only in newer versions. after effects error asked to create unknown property of type

"ADBE Mask" , "ADBE Effect" , "ADBE Paint" , etc. Wrong: passing a custom string that AE doesn't recognize. if (layer