diff --git a/webapp/src/mutator.test.ts b/webapp/src/mutator.test.ts
index 4a3870ba3..86aac8744 100644
--- a/webapp/src/mutator.test.ts
+++ b/webapp/src/mutator.test.ts
@@ -38,7 +38,7 @@ describe('Mutator', () => {
         const board = TestBlockFactory.createBoard()
 
         FetchMock.fn.mockReturnValueOnce(FetchMock.jsonResponse(JSON.stringify([card])))
-        FetchMock.fn.mockReturnValueOnce(FetchMock.jsonResponse(JSON.stringify({})))
+        FetchMock.fn.mockReturnValueOnce(FetchMock.jsonResponse(JSON.stringify([])))
         const [newBlocks, newCardID] = await mutator.duplicateCard(card.id, board)
 
         expect(newBlocks).toHaveLength(1)
diff --git a/webapp/src/mutator.ts b/webapp/src/mutator.ts
index eb7187999..81d8a054d 100644
--- a/webapp/src/mutator.ts
+++ b/webapp/src/mutator.ts
@@ -682,7 +682,12 @@ class Mutator {
             newBlocks,
             description,
             async (respBlocks: Block[]) => {
-                await afterRedo?.(respBlocks[0].id)
+                const card = respBlocks.find((block) => block.type === 'card')
+                if (card) {
+                    await afterRedo?.(card.id)
+                } else {
+                    Utils.logError('card not found for opening.')
+                }
             },
             beforeUndo,
         )