--- a/gfx/layers/AnimationInfo.cpp
+++ b/gfx/layers/AnimationInfo.cpp
@@ -38,16 +38,21 @@ AnimationInfo::AddAnimation()
   // Here generates a new id when the first animation is added and
   // this id is used to represent the animations in this layer.
   EnsureAnimationsId();
 
   MOZ_ASSERT(!mPendingAnimations, "should have called ClearAnimations first");
 
   Animation* anim = mAnimations.AppendElement();
 
+  if (mManager->AsWebRenderLayerManager()) {
+    mManager->AsWebRenderLayerManager()->
+      KeepCompositorAnimationsIdAlive(mCompositorAnimationsId);
+  }
+
   mMutated = true;
 
   return anim;
 }
 
 Animation*
 AnimationInfo::AddAnimationForNextTransaction()
 {

--- a/gfx/layers/wr/WebRenderLayerManager.cpp
+++ b/gfx/layers/wr/WebRenderLayerManager.cpp
@@ -960,16 +960,22 @@ WebRenderLayerManager::DiscardImages()
 
 void
 WebRenderLayerManager::AddCompositorAnimationsIdForDiscard(uint64_t aId)
 {
   mDiscardedCompositorAnimationsIds.AppendElement(aId);
 }
 
 void
+WebRenderLayerManager::KeepCompositorAnimationsIdAlive(uint64_t aId)
+{
+  mDiscardedCompositorAnimationsIds.RemoveElement(aId);
+}
+
+void
 WebRenderLayerManager::DiscardCompositorAnimations()
 {
   if (WrBridge()->IPCOpen() && !mDiscardedCompositorAnimationsIds.IsEmpty()) {
     WrBridge()->
       SendDeleteCompositorAnimations(mDiscardedCompositorAnimationsIds);
   }
   mDiscardedCompositorAnimationsIds.Clear();
 }

--- a/gfx/layers/wr/WebRenderLayerManager.h
+++ b/gfx/layers/wr/WebRenderLayerManager.h
@@ -169,16 +169,19 @@ public:
   // transaction or destruction
   void AddImageKeyForDiscard(wr::ImageKey);
   void DiscardImages();
   void DiscardLocalImages();
 
   // Before destroying a layer with animations, add its compositorAnimationsId
   // to a list of ids that will be discarded on the next transaction
   void AddCompositorAnimationsIdForDiscard(uint64_t aId);
+  // If the animations are valid and running on the compositor,
+  // we should keep the compositorAnimationsId alive on the compositor side.
+  void KeepCompositorAnimationsIdAlive(uint64_t aId);
   void DiscardCompositorAnimations();
 
   WebRenderBridgeChild* WrBridge() const { return mWrChild; }
 
   virtual void Mutated(Layer* aLayer) override;
   virtual void MutatedSimple(Layer* aLayer) override;
 
   void Hold(Layer* aLayer);