fixes 'GetEditTarget'`` errors when using stage-in-memory mode

Author: ooctipus

source/isaaclab/config/extension.toml

@@ -1,7 +1,7 @@
 [package]
 
 # Note: Semantic Versioning is used: https://semver.org/
-version = "3.4.0"
+version = "3.4.1"
 
 # Description
 title = "Isaac Lab framework for Robot Learning"

source/isaaclab/docs/CHANGELOG.rst

@@ -2,6 +2,17 @@ Changelog
 ---------
 
 
+3.4.1 (2026-02-21)
+~~~~~~~~~~~~~~~~~~
+
+Fixed
+^^^^^
+
+* Fixed :func:`~isaaclab.sim.utils.add_labels` to use :class:`UsdSemantics.LabelsAPI` directly
+  instead of the Replicator API for Isaac Sim 5.0+. This resolves ``'NoneType' object has no
+  attribute 'GetEditTarget'`` errors when using stage-in-memory mode.
+
+
 3.4.0 (2026-02-18)
 ~~~~~~~~~~~~~~~~~~
 

source/isaaclab/isaaclab/sim/utils/semantics.py

@@ -27,12 +27,12 @@
 def add_labels(prim: Usd.Prim, labels: list[str], instance_name: str = "class", overwrite: bool = True) -> None:
     """Apply semantic labels to a prim using the :class:`UsdSemantics.LabelsAPI`.
 
-    This function is a wrapper around the :func:`omni.replicator.core.functional.modify.semantics` function.
-    It applies the labels to the prim using the :class:`UsdSemantics.LabelsAPI`.
+    For Isaac Sim 5.0+, this uses :class:`UsdSemantics.LabelsAPI` directly on the prim.
+    For earlier versions, it falls back to the deprecated :class:`Semantics.SemanticsAPI`.
 
     .. versionadded:: 2.3.0
         This function is available in Isaac Sim 5.0 and later, which introduces the :class:`UsdSemantics.LabelsAPI`.
-        For previous versions, the function falls back to use the deprecated :class:`UsdSemantics.SemanticsAPI` instead.
+        For previous versions, the function falls back to use the deprecated :class:`Semantics.SemanticsAPI` instead.
 
     Example:
         >>> prim = sim_utils.create_prim("/World/Test/Sphere", "Sphere", stage=stage, attributes={"radius": 10.0})
@@ -45,44 +45,37 @@ def add_labels(prim: Usd.Prim, labels: list[str], instance_name: str = "class",
         overwrite: Whether to overwrite existing labels for this instance. If False,
           the new labels are appended to existing ones (if any). Defaults to True.
     """
-    # Try modern approach (Isaac Sim >= 5.0)
-    try:
-        import omni.replicator.core.functional as rep_functional
-
-        mode = "replace" if overwrite else "add"
-        rep_functional.modify.semantics(prim, {instance_name: labels}, mode=mode)
-
-        return
-    except (ModuleNotFoundError, ImportError) as e:
-        # check if we are using isaac sim 5.0
-        if get_isaac_sim_version().major >= 5:
-            logger.warning(
-                f"Failed to add labels to prim {prim.GetPath()} using Replicator API: {e}. "
-                "\nPlease ensure Replicator API is enabled by passing '--enable_cameras' to the AppLauncher."
-                "\nFalling back to legacy approach."
-            )
-
-    # Try legacy approach (Isaac Sim < 5.0)
-    try:
+    isaac_sim_version = get_isaac_sim_version()
+
+    if isaac_sim_version.major >= 5:
+        # Isaac Sim 5.0+: Use UsdSemantics.LabelsAPI directly
+        # This uses the prim's own stage reference, avoiding issues with stale global stage references
+        # that can occur with the Replicator API when using stage-in-memory mode.
+        labels_api = UsdSemantics.LabelsAPI.Apply(prim, instance_name)
+        labels_attr = labels_api.CreateLabelsAttr()
+        if overwrite:
+            labels_attr.Set(labels)
+        else:
+            existing = labels_attr.Get()
+            if existing:
+                combined = list(existing) + [lbl for lbl in labels if lbl not in existing]
+                labels_attr.Set(combined)
+            else:
+                labels_attr.Set(labels)
+    else:
+        # Isaac Sim < 5.0: Use legacy Semantics.SemanticsAPI
         import Semantics
 
-        # check we have only one label
         if len(labels) != 1:
-            raise ValueError(f"Only one label can be applied to a prim. Received: {labels}")
-        # set the semantic API for the instance
-        instance_name = f"{instance_name}_{labels[0]}"
-        sem = Semantics.SemanticsAPI.Apply(prim, instance_name)
-        # create semantic type and data attributes
+            raise ValueError(
+                f"Legacy SemanticsAPI only supports one label per instance. Received {len(labels)}: {labels}"
+            )
+        sem_instance_name = f"{instance_name}_{labels[0]}"
+        sem = Semantics.SemanticsAPI.Apply(prim, sem_instance_name)
         sem.CreateSemanticTypeAttr()
         sem.CreateSemanticDataAttr()
-        sem.GetSemanticTypeAttr().Set(instance_name)
+        sem.GetSemanticTypeAttr().Set(sem_instance_name)
         sem.GetSemanticDataAttr().Set(labels[0])
-    except Exception as e:
-        logger.warning(
-            f"Failed to add labels to prim {prim.GetPath()} using legacy API: {e}. "
-            "\nSemantics functionality may not be available in this Isaac Sim version."
-            " Please open an issue at https://github.com/isaac-sim/IsaacLab/issues if you believe this is a bug."
-        )
 
 
 def get_labels(prim: Usd.Prim) -> dict[str, list[str]]: