fix: handle non-isomorphic block element update

vuejs · edison1105 · Jun 25, 2026 · Jun 24, 2026 · Jun 24, 2026 · Jun 24, 2026
commit 303de0e6504d2737841cdca7cb838b952f74ddd0
diff --git a/packages/runtime-core/__tests__/rendererOptimizedMode.spec.ts b/packages/runtime-core/__tests__/rendererOptimizedMode.spec.ts
@@ -825,6 +825,24 @@ describe('renderer: optimized mode', () => {
     expect(inner(root)).toBe('<div><div><span>loading</span></div></div>')
   })
 
+  // #6385
+  test('should fall back to full diff when the user patches a compiled slot', () => {
+    render(h('div', { id: 'placeholder' }), root)
+
+    render(
+      (openBlock(),
+      createElementBlock('div', { id: 'resolved' }, [
+        createTextVNode('hello '),
+        createElementVNode('button', null, '0', PatchFlags.TEXT),
+      ])),
+      root,
+    )
+
+    expect(inner(root)).toBe(
+      '<div id="resolved">hello <button>0</button></div>',
+    )
+  })
+
   // #3828
   test('patch Suspense in optimized mode w/ nested dynamic nodes', async () => {
     const show = ref(false)

diff --git a/packages/runtime-core/src/renderer.ts b/packages/runtime-core/src/renderer.ts
@@ -855,8 +855,15 @@ function baseCreateRenderer(
     }
     parentComponent && toggleRecurse(parentComponent, true)
 
-    if (__DEV__ && isHmrUpdating) {
-      // HMR updated, force full diff
+    // #6385 the old vnode may be a user-wrapped non-isomorphic block
+    const isFullDiffRequired = !(
+      dynamicChildren &&
+      n1.dynamicChildren &&
+      n1.dynamicChildren.length === dynamicChildren.length
+    )
+
+    // HMR updated, force full diff
+    if (isFullDiffRequired || (__DEV__ && isHmrUpdating)) {
       patchFlag = 0
       optimized = false
       dynamicChildren = null
@@ -871,33 +878,32 @@ function baseCreateRenderer(
       hostSetElementText(el, '')
     }
 
-    if (dynamicChildren) {
-      patchBlockChildren(
-        n1.dynamicChildren!,
-        dynamicChildren,
+    if (isFullDiffRequired) {
+      patchChildren(
+        n1,
+        n2,
         el,
+        null,
         parentComponent,
         parentSuspense,
         resolveChildrenNamespace(n2, namespace),
         slotScopeIds,
+        false,
       )
-      if (__DEV__) {
-        // necessary for HMR
-        traverseStaticChildren(n1, n2)
-      }
-    } else if (!optimized) {
-      // full diff
-      patchChildren(
-        n1,
-        n2,
+    } else {
+      patchBlockChildren(
+        n1.dynamicChildren!,
+        dynamicChildren!,
         el,
-        null,
         parentComponent,
         parentSuspense,
         resolveChildrenNamespace(n2, namespace),
         slotScopeIds,
-        false,
       )
+      if (__DEV__) {
+        // necessary for HMR
+        traverseStaticChildren(n1, n2)
+      }
     }
 
     if (patchFlag > 0) {