--- a/gfx/layers/apz/src/APZCTreeManager.cpp
+++ b/gfx/layers/apz/src/APZCTreeManager.cpp
@@ -399,20 +399,25 @@ APZCTreeManager::PushStateToWR(wr::WebRe
           return;
         }
         AsyncPanZoomController* apzc = aNode->GetApzc();
         MOZ_ASSERT(apzc);
 
         if (aNode->GetLayersId() != lastLayersId) {
           // If we walked into or out of a subtree, we need to get the new
           // pipeline id.
+          const LayerTreeState* state = CompositorBridgeParent::GetIndirectShadowTree(aNode->GetLayersId());
+          if (!(state && state->mWrBridge)) {
+            // During shutdown we might have layer tree information for stuff
+            // that has already been torn down. In that case just skip over
+            // those layers.
+            return;
+          }
+          lastPipelineId = state->mWrBridge->PipelineId();
           lastLayersId = aNode->GetLayersId();
-          const LayerTreeState* state = CompositorBridgeParent::GetIndirectShadowTree(lastLayersId);
-          MOZ_ASSERT(state && state->mWrBridge);
-          lastPipelineId = state->mWrBridge->PipelineId();
         }
 
         // Use a 0 presShellId because when we do a lookup in this map for the
         // scrollbar below we don't have (or care about) the presShellId.
         ScrollableLayerGuid guid(lastLayersId, 0, apzc->GetGuid().mScrollId);
         httnMap.insert(std::make_pair(guid, aNode));
 
         ParentLayerPoint layerTranslation = apzc->GetCurrentAsyncTransform(