diff --git a/scripts/addons_core/pose_library/__init__.py b/scripts/addons_core/pose_library/__init__.py
index ad6dfa0dc8b..462e453250a 100644
--- a/scripts/addons_core/pose_library/__init__.py
+++ b/scripts/addons_core/pose_library/__init__.py
@@ -23,7 +23,7 @@ bl_info = {
 from typing import List, Tuple
 
 _need_reload = "operators" in locals()
-from . import gui, keymaps, operators, conversion
+from . import gui, keymaps, operators
 
 if _need_reload:
     import importlib
@@ -31,7 +31,6 @@ if _need_reload:
     gui = importlib.reload(gui)
     keymaps = importlib.reload(keymaps)
     operators = importlib.reload(operators)
-    conversion = importlib.reload(conversion)
 
 import bpy
 
diff --git a/scripts/addons_core/pose_library/conversion.py b/scripts/addons_core/pose_library/conversion.py
deleted file mode 100644
index 08c250e578a..00000000000
--- a/scripts/addons_core/pose_library/conversion.py
+++ /dev/null
@@ -1,62 +0,0 @@
-# SPDX-FileCopyrightText: 2021-2023 Blender Foundation
-#
-# SPDX-License-Identifier: GPL-2.0-or-later
-
-"""
-Pose Library - Conversion of old pose libraries.
-"""
-
-from typing import Optional
-from collections.abc import Collection
-
-if "pose_creation" not in locals():
-    from . import pose_creation
-else:
-    import importlib
-
-    pose_creation = importlib.reload(pose_creation)
-
-import bpy
-from bpy.types import (
-    Action,
-    TimelineMarker,
-)
-
-
-def convert_old_poselib(old_poselib: Action) -> Collection[Action]:
-    """Convert an old-style pose library to a set of pose Actions.
-
-    Old pose libraries were one Action with multiple pose markers. Each pose
-    marker will be converted to an Action by itself and marked as asset.
-    """
-
-    pose_assets = [action for marker in old_poselib.pose_markers if (action := convert_old_pose(old_poselib, marker))]
-
-    # Mark all Actions as assets in one go. Ideally this would be done on an
-    # appropriate frame in the scene (to set up things like the background
-    # colour), but the old-style poselib doesn't contain such information. All
-    # we can do is just render on the current frame.
-    context_override = {'selected_ids': pose_assets}
-    with bpy.context.temp_override(**context_override):
-        bpy.ops.asset.mark()
-
-    return pose_assets
-
-
-def convert_old_pose(old_poselib: Action, marker: TimelineMarker) -> Optional[Action]:
-    """Convert an old-style pose library pose to a pose action."""
-
-    frame: int = marker.frame
-    action: Optional[Action] = None
-
-    for fcurve in old_poselib.fcurves:
-        key = pose_creation.find_keyframe(fcurve, frame)
-        if not key:
-            continue
-
-        if action is None:
-            action = bpy.data.actions.new(marker.name)
-
-        pose_creation.create_single_key_fcurve(action, fcurve, key)
-
-    return action
diff --git a/scripts/addons_core/pose_library/gui.py b/scripts/addons_core/pose_library/gui.py
index 0dad2780d6b..b4142f8c4c1 100644
--- a/scripts/addons_core/pose_library/gui.py
+++ b/scripts/addons_core/pose_library/gui.py
@@ -28,6 +28,7 @@ class VIEW3D_MT_pose_modify(Menu):
         layout.operator("poselib.asset_modify", text="Add Selected Bones").mode = "ADD"
         layout.operator("poselib.asset_modify", text="Remove Selected Bones").mode = "REMOVE"
 
+
 class PoseLibraryPanel:
     @classmethod
     def pose_library_panel_poll(cls, context: Context) -> bool:
@@ -132,8 +133,6 @@ class DOPESHEET_PT_asset_panel(PoseLibraryPanel, Panel):
             row.operator("poselib.restore_previous_action", text="", icon='LOOP_BACK')
         col.operator("poselib.copy_as_asset", icon="COPYDOWN")
 
-        layout.operator("poselib.convert_old_poselib")
-
 
 def pose_library_list_item_asset_menu(self: UIList, context: Context) -> None:
     layout = self.layout
diff --git a/scripts/addons_core/pose_library/operators.py b/scripts/addons_core/pose_library/operators.py
index 57f125e6721..87649268915 100644
--- a/scripts/addons_core/pose_library/operators.py
+++ b/scripts/addons_core/pose_library/operators.py
@@ -288,75 +288,8 @@ class POSELIB_OT_pose_asset_select_bones(PoseAssetUser, Operator):
         return tip_("Deselect those bones that are used in this pose")
 
 
-class POSELIB_OT_convert_old_poselib(Operator):
-    bl_idname = "poselib.convert_old_poselib"
-    bl_label = "Convert Legacy Pose Library"
-    bl_description = "Create a pose asset for each pose marker in the current action"
-    bl_options = {'REGISTER', 'UNDO'}
-
-    @classmethod
-    def poll(cls, context: Context) -> bool:
-        action = context.object and context.object.animation_data and context.object.animation_data.action
-        if not action:
-            cls.poll_message_set("Active object has no Action")
-            return False
-        if not action.pose_markers:
-            cls.poll_message_set(tip_("Action %r is not a legacy pose library") % action.name)
-            return False
-        return True
-
-    def execute(self, context: Context) -> Set[str]:
-        from . import conversion
-
-        old_poselib = context.object.animation_data.action
-        new_actions = conversion.convert_old_poselib(old_poselib)
-
-        if not new_actions:
-            self.report({'ERROR'}, "Unable to convert to pose assets")
-            return {'CANCELLED'}
-
-        self.report({'INFO'}, tip_("Converted %d poses to pose assets") % len(new_actions))
-        return {'FINISHED'}
-
-
-class POSELIB_OT_convert_old_object_poselib(Operator):
-    bl_idname = "poselib.convert_old_object_poselib"
-    bl_label = "Convert Legacy Pose Library"
-    bl_description = "Create a pose asset for each pose marker in this legacy pose library data-block"
-
-    # Mark this one as "internal", as it converts `context.object.pose_library`
-    # instead of its current animation Action.
-    bl_options = {'REGISTER', 'UNDO', 'INTERNAL'}
-
-    @classmethod
-    def poll(cls, context: Context) -> bool:
-        action = context.object and context.object.pose_library
-        if not action:
-            cls.poll_message_set("Active object has no pose library Action")
-            return False
-        if not action.pose_markers:
-            cls.poll_message_set(tip_("Action %r is not a legacy pose library") % action.name)
-            return False
-        return True
-
-    def execute(self, context: Context) -> Set[str]:
-        from . import conversion
-
-        old_poselib = context.object.pose_library
-        new_actions = conversion.convert_old_poselib(old_poselib)
-
-        if not new_actions:
-            self.report({'ERROR'}, "Unable to convert to pose assets")
-            return {'CANCELLED'}
-
-        self.report({'INFO'}, tip_("Converted %d poses to pose assets") % len(new_actions))
-        return {'FINISHED'}
-
-
 classes = (
     ASSET_OT_assign_action,
-    POSELIB_OT_convert_old_poselib,
-    POSELIB_OT_convert_old_object_poselib,
     POSELIB_OT_copy_as_asset,
     POSELIB_OT_paste_asset,
     POSELIB_OT_pose_asset_select_bones,
diff --git a/scripts/addons_core/pose_library/pose_creation.py b/scripts/addons_core/pose_library/pose_creation.py
index 2c473ae06d2..9f8bcee8353 100644
--- a/scripts/addons_core/pose_library/pose_creation.py
+++ b/scripts/addons_core/pose_library/pose_creation.py
@@ -91,8 +91,6 @@ class PoseActionCreator:
 
     def _create_new_action(self) -> Action:
         dst_action = bpy.data.actions.new(self.params.new_asset_name)
-        if self.params.src_action:
-            dst_action.id_root = self.params.src_action.id_root
         dst_action.user_clear()  # actions.new() sets users=1, but marking as asset also increments user count.
         return dst_action