Do not invoke server actions twice when dynamicIO is enabled

packages/next/src/server/base-server.ts

@@ -3038,7 +3038,8 @@ export default abstract class Server<
           if (
             !cache &&
             !isPrefetchRSCRequest &&
-            routeModule?.definition.kind === RouteKind.APP_PAGE
+            routeModule?.definition.kind === RouteKind.APP_PAGE &&
+            !isServerAction
           ) {
             req.headers[RSC_HEADER] = '1'
             req.headers[NEXT_ROUTER_PREFETCH_HEADER] = '1'

test/e2e/app-dir/dynamic-io/app/server-action/action.ts

@@ -0,0 +1,5 @@
+'use server'
+
+export async function action(value: string) {
+  return value
+}

test/e2e/app-dir/dynamic-io/app/server-action/page.tsx

@@ -0,0 +1,16 @@
+'use client'
+
+import { useActionState } from 'react'
+import { action } from './action'
+
+export default function Page() {
+  const [result, formAction] = useActionState(() => action('result'), 'initial')
+
+  return (
+    <form action={formAction}>
+      <h1>Server Action with Dynamic IO</h1>
+      <button>Submit</button>
+      <p>{result}</p>
+    </form>
+  )
+}

test/e2e/app-dir/dynamic-io/dynamic-io.server-action.test.ts

@@ -0,0 +1,18 @@
+import { nextTestSetup } from 'e2e-utils'
+import { retry } from 'next-test-utils'
+
+describe('dynamic-io', () => {
+  const { next } = nextTestSetup({
+    files: __dirname,
+  })
+
+  it('should not fail decoding server action arguments', async () => {
+    const browser = await next.browser('/server-action')
+    expect(await browser.elementByCss('p').text()).toBe('initial')
+    await browser.elementByCss('button').click()
+
+    await retry(async () => {
+      expect(await browser.elementByCss('p').text()).toBe('result')
+    })
+  })
+})