diff --git a/api/Avalonia.nupkg.xml b/api/Avalonia.nupkg.xml
index 15e956bdc6..272f5d71c7 100644
--- a/api/Avalonia.nupkg.xml
+++ b/api/Avalonia.nupkg.xml
@@ -415,6 +415,24 @@
     <Left>baseline/Avalonia/lib/net10.0/Avalonia.Controls.dll</Left>
     <Right>current/Avalonia/lib/net10.0/Avalonia.Controls.dll</Right>
   </Suppression>
+  <Suppression>
+    <DiagnosticId>CP0002</DiagnosticId>
+    <Target>M:Avalonia.Controls.Primitives.OverlayPopupHost.ConfigurePosition(Avalonia.Visual,Avalonia.Controls.PlacementMode,Avalonia.Point,Avalonia.Controls.Primitives.PopupPositioning.PopupAnchor,Avalonia.Controls.Primitives.PopupPositioning.PopupGravity,Avalonia.Controls.Primitives.PopupPositioning.PopupPositionerConstraintAdjustment,System.Nullable{Avalonia.Rect})</Target>
+    <Left>baseline/Avalonia/lib/net10.0/Avalonia.Controls.dll</Left>
+    <Right>current/Avalonia/lib/net10.0/Avalonia.Controls.dll</Right>
+  </Suppression>
+  <Suppression>
+    <DiagnosticId>CP0002</DiagnosticId>
+    <Target>M:Avalonia.Controls.Primitives.OverlayPopupHost.CreatePopupHost(Avalonia.Visual,Avalonia.IAvaloniaDependencyResolver)</Target>
+    <Left>baseline/Avalonia/lib/net10.0/Avalonia.Controls.dll</Left>
+    <Right>current/Avalonia/lib/net10.0/Avalonia.Controls.dll</Right>
+  </Suppression>
+  <Suppression>
+    <DiagnosticId>CP0002</DiagnosticId>
+    <Target>M:Avalonia.Controls.Primitives.PopupRoot.ConfigurePosition(Avalonia.Visual,Avalonia.Controls.PlacementMode,Avalonia.Point,Avalonia.Controls.Primitives.PopupPositioning.PopupAnchor,Avalonia.Controls.Primitives.PopupPositioning.PopupGravity,Avalonia.Controls.Primitives.PopupPositioning.PopupPositionerConstraintAdjustment,System.Nullable{Avalonia.Rect})</Target>
+    <Left>baseline/Avalonia/lib/net10.0/Avalonia.Controls.dll</Left>
+    <Right>current/Avalonia/lib/net10.0/Avalonia.Controls.dll</Right>
+  </Suppression>
   <Suppression>
     <DiagnosticId>CP0002</DiagnosticId>
     <Target>M:Avalonia.Controls.Primitives.TextSearch.GetText(Avalonia.Controls.Control)</Target>
@@ -817,6 +835,24 @@
     <Left>baseline/Avalonia/lib/net8.0/Avalonia.Controls.dll</Left>
     <Right>current/Avalonia/lib/net8.0/Avalonia.Controls.dll</Right>
   </Suppression>
+  <Suppression>
+    <DiagnosticId>CP0002</DiagnosticId>
+    <Target>M:Avalonia.Controls.Primitives.OverlayPopupHost.ConfigurePosition(Avalonia.Visual,Avalonia.Controls.PlacementMode,Avalonia.Point,Avalonia.Controls.Primitives.PopupPositioning.PopupAnchor,Avalonia.Controls.Primitives.PopupPositioning.PopupGravity,Avalonia.Controls.Primitives.PopupPositioning.PopupPositionerConstraintAdjustment,System.Nullable{Avalonia.Rect})</Target>
+    <Left>baseline/Avalonia/lib/net8.0/Avalonia.Controls.dll</Left>
+    <Right>current/Avalonia/lib/net8.0/Avalonia.Controls.dll</Right>
+  </Suppression>
+  <Suppression>
+    <DiagnosticId>CP0002</DiagnosticId>
+    <Target>M:Avalonia.Controls.Primitives.OverlayPopupHost.CreatePopupHost(Avalonia.Visual,Avalonia.IAvaloniaDependencyResolver)</Target>
+    <Left>baseline/Avalonia/lib/net8.0/Avalonia.Controls.dll</Left>
+    <Right>current/Avalonia/lib/net8.0/Avalonia.Controls.dll</Right>
+  </Suppression>
+  <Suppression>
+    <DiagnosticId>CP0002</DiagnosticId>
+    <Target>M:Avalonia.Controls.Primitives.PopupRoot.ConfigurePosition(Avalonia.Visual,Avalonia.Controls.PlacementMode,Avalonia.Point,Avalonia.Controls.Primitives.PopupPositioning.PopupAnchor,Avalonia.Controls.Primitives.PopupPositioning.PopupGravity,Avalonia.Controls.Primitives.PopupPositioning.PopupPositionerConstraintAdjustment,System.Nullable{Avalonia.Rect})</Target>
+    <Left>baseline/Avalonia/lib/net8.0/Avalonia.Controls.dll</Left>
+    <Right>current/Avalonia/lib/net8.0/Avalonia.Controls.dll</Right>
+  </Suppression>
   <Suppression>
     <DiagnosticId>CP0002</DiagnosticId>
     <Target>M:Avalonia.Controls.Primitives.TextSearch.GetText(Avalonia.Controls.Control)</Target>
diff --git a/src/Avalonia.Base/Diagnostics/ObsoletionMessages.cs b/src/Avalonia.Base/Diagnostics/ObsoletionMessages.cs
deleted file mode 100644
index bfada91abe..0000000000
--- a/src/Avalonia.Base/Diagnostics/ObsoletionMessages.cs
+++ /dev/null
@@ -1,12 +0,0 @@
-using System;
-using System.Collections.Generic;
-using System.Linq;
-using System.Text;
-using System.Threading.Tasks;
-
-namespace Avalonia.Diagnostics;
-
-internal static class ObsoletionMessages
-{
-    public const string MayBeRemovedInAvalonia12 = "This API may be removed in Avalonia 12. If you depend on this API, please open an issue with details of your use-case.";
-}
diff --git a/src/Avalonia.Controls/Primitives/IPopupHost.cs b/src/Avalonia.Controls/Primitives/IPopupHost.cs
index c4f992363e..7ed87682a6 100644
--- a/src/Avalonia.Controls/Primitives/IPopupHost.cs
+++ b/src/Avalonia.Controls/Primitives/IPopupHost.cs
@@ -1,11 +1,9 @@
 using System;
 using Avalonia.Controls.Presenters;
 using Avalonia.Controls.Primitives.PopupPositioning;
-using Avalonia.Diagnostics;
 using Avalonia.Input;
 using Avalonia.Media;
 using Avalonia.Metadata;
-using Avalonia.VisualTree;
 
 namespace Avalonia.Controls.Primitives
 {
@@ -17,8 +15,7 @@ namespace Avalonia.Controls.Primitives
     /// (<see cref="PopupRoot"/>) or an <see cref="OverlayPopupHost"/> which is created
     /// on an <see cref="OverlayLayer"/>.
     /// </remarks>
-    [NotClientImplementable]
-    [Unstable(ObsoletionMessages.MayBeRemovedInAvalonia12)]
+    [PrivateApi]
     public interface IPopupHost : IDisposable, IFocusScope
     {
         /// <summary>
diff --git a/src/Avalonia.Controls/Primitives/OverlayPopupHost.cs b/src/Avalonia.Controls/Primitives/OverlayPopupHost.cs
index 3e4fee20b7..d52e0e4d98 100644
--- a/src/Avalonia.Controls/Primitives/OverlayPopupHost.cs
+++ b/src/Avalonia.Controls/Primitives/OverlayPopupHost.cs
@@ -121,16 +121,6 @@ namespace Avalonia.Controls.Primitives
             // Nothing to do here: overlay popups are implemented inside the window.
         }
 
-        [Unstable(ObsoletionMessages.MayBeRemovedInAvalonia12)]
-        public void ConfigurePosition(Visual target, PlacementMode placement, Point offset,
-            PopupAnchor anchor = PopupAnchor.None, PopupGravity gravity = PopupGravity.None,
-            PopupPositionerConstraintAdjustment constraintAdjustment = PopupPositionerConstraintAdjustment.All,
-            Rect? rect = null)
-        {
-            ((IPopupHost)this).ConfigurePosition(new PopupPositionRequest(target, placement, offset, anchor, gravity,
-                constraintAdjustment, rect, null));
-        }
-
         /// <inheritdoc />
         void IPopupHost.ConfigurePosition(PopupPositionRequest positionRequest)
         {
@@ -191,12 +181,8 @@ namespace Avalonia.Controls.Primitives
 
         double IManagedPopupPositionerPopup.Scaling => 1;
 
-        // TODO12: mark PrivateAPI or internal.
-        [Unstable("PopupHost is considered an internal API. Use Popup or any Popup-based controls (Flyout, Tooltip) instead.")]
-        public static IPopupHost CreatePopupHost(Visual target, IAvaloniaDependencyResolver? dependencyResolver)
-            => CreatePopupHost(target, dependencyResolver, false);
-
-        internal static IPopupHost CreatePopupHost(Visual target, IAvaloniaDependencyResolver? dependencyResolver, bool shouldUseOverlayLayer)
+        [PrivateApi]
+        public static IPopupHost CreatePopupHost(Visual target, IAvaloniaDependencyResolver? dependencyResolver, bool shouldUseOverlayLayer)
         {
             if (!shouldUseOverlayLayer)
             {
diff --git a/src/Avalonia.Controls/Primitives/PopupPositioning/IPopupPositioner.cs b/src/Avalonia.Controls/Primitives/PopupPositioning/IPopupPositioner.cs
index a0b853f2dc..82dead1ed5 100644
--- a/src/Avalonia.Controls/Primitives/PopupPositioning/IPopupPositioner.cs
+++ b/src/Avalonia.Controls/Primitives/PopupPositioning/IPopupPositioner.cs
@@ -66,7 +66,6 @@ namespace Avalonia.Controls.Primitives.PopupPositioning
     /// requirement that a popup must intersect with or be at least partially adjacent to its parent
     /// surface.
     /// </remarks>
-    [Unstable(ObsoletionMessages.MayBeRemovedInAvalonia12)]
     public record struct PopupPositionerParameters
     {
         private PopupGravity _gravity;
diff --git a/src/Avalonia.Controls/Primitives/PopupPositioning/PopupPositionRequest.cs b/src/Avalonia.Controls/Primitives/PopupPositioning/PopupPositionRequest.cs
index 35e15e3057..ab1002cb9b 100644
--- a/src/Avalonia.Controls/Primitives/PopupPositioning/PopupPositionRequest.cs
+++ b/src/Avalonia.Controls/Primitives/PopupPositioning/PopupPositionRequest.cs
@@ -4,7 +4,6 @@ using Avalonia.Metadata;
 namespace Avalonia.Controls.Primitives.PopupPositioning;
 
 [PrivateApi]
-[Unstable(ObsoletionMessages.MayBeRemovedInAvalonia12)]
 public class PopupPositionRequest
 {
     internal PopupPositionRequest(Visual target, PlacementMode placement)
diff --git a/src/Avalonia.Controls/Primitives/PopupRoot.cs b/src/Avalonia.Controls/Primitives/PopupRoot.cs
index f88ed0b93b..6dc4627f0c 100644
--- a/src/Avalonia.Controls/Primitives/PopupRoot.cs
+++ b/src/Avalonia.Controls/Primitives/PopupRoot.cs
@@ -136,17 +136,6 @@ namespace Avalonia.Controls.Primitives
             }
         }
 
-        [Unstable(ObsoletionMessages.MayBeRemovedInAvalonia12)]
-        public void ConfigurePosition(Visual target, PlacementMode placement, Point offset,
-            PopupAnchor anchor = PopupAnchor.None,
-            PopupGravity gravity = PopupGravity.None,
-            PopupPositionerConstraintAdjustment constraintAdjustment = PopupPositionerConstraintAdjustment.All,
-            Rect? rect = null)
-        {
-            ((IPopupHost)this).ConfigurePosition(new PopupPositionRequest(target, placement, offset, anchor, gravity,
-                constraintAdjustment, rect, null));
-        }
-
         void IPopupHost.ConfigurePosition(PopupPositionRequest request)
         {
             _popupPositionRequest = request;