From 1594b6dcf60e72a1c82b77e0ad4f90f363bef812 Mon Sep 17 00:00:00 2001
From: Yury Semikhatsky <yurys@chromium.org>
Date: Fri, 15 May 2026 15:12:26 -0700
Subject: [PATCH] fix(mcp): report missing ffmpeg distinctly from missing
 browser

The MCP launch error handler was rewriting any `Executable doesn't exist`
error into `Browser "<channel>" is not installed`, but the registry uses
the same prefix for ffmpeg too. When `recordVideo` was enabled and ffmpeg
was missing, users were told to install a browser that was already there.

Disambiguate the rewrite by the executable path so ffmpeg gets its own
message pointing at `install-browser ffmpeg`.

Fixes: https://github.com/microsoft/playwright/issues/40862
---
 .../src/tools/mcp/browserFactory.ts           | 21 ++++++-----
 tests/mcp/video.spec.ts                       | 35 +++++++++++++++++++
 2 files changed, 47 insertions(+), 9 deletions(-)

diff --git a/packages/playwright-core/src/tools/mcp/browserFactory.ts b/packages/playwright-core/src/tools/mcp/browserFactory.ts
index ed4dc7ffe5fba..2f33851a7c566 100644
--- a/packages/playwright-core/src/tools/mcp/browserFactory.ts
+++ b/packages/playwright-core/src/tools/mcp/browserFactory.ts
@@ -96,8 +96,7 @@ async function createIsolatedBrowser(config: FullConfig, clientInfo: ClientInfo)
     handleSIGINT: false,
     handleSIGTERM: false,
   }).catch(error => {
-    if (error.message.includes('Executable doesn\'t exist'))
-      throwBrowserIsNotInstalledError(config);
+    throwIfExecutableMissing(error, config);
     throw error;
   });
   return browser;
@@ -171,8 +170,7 @@ async function createPersistentBrowser(config: FullConfig, clientInfo: ClientInf
     const browser = browserContext.browser()!;
     return browser;
   } catch (error: any) {
-    if (error.message.includes('Executable doesn\'t exist'))
-      throwBrowserIsNotInstalledError(config);
+    throwIfExecutableMissing(error, config);
     if (error.message.includes('cannot open shared object file: No such file or directory')) {
       const browserName = launchOptions.channel ?? config.browser.browserName;
       throw new Error(`Missing system dependencies required to run browser ${browserName}. Install them with: sudo npx playwright install-deps ${browserName}`);
@@ -236,10 +234,15 @@ export function isProfileLocked(userDataDir: string): boolean {
   }
 }
 
-function throwBrowserIsNotInstalledError(config: FullConfig): never {
-  const channel = config.browser.launchOptions?.channel ?? config.browser.browserName;
+function throwIfExecutableMissing(error: Error, config: FullConfig): void {
+  // The "Executable doesn't exist" prefix is shared by all managed binaries
+  // (browser, ffmpeg, winldd). Disambiguate by the path so the user is told
+  // which dependency to install.
+  if (!error.message.includes(`Executable doesn't exist`))
+    return;
+  const target = error.message.includes('ffmpeg') ? 'ffmpeg' : (config.browser.launchOptions?.channel ?? config.browser.browserName);
+  const label = target === 'ffmpeg' ? 'FFmpeg' : `Browser "${target}"`;
   if (config.skillMode)
-    throw new Error(`Browser "${channel}" is not installed. Run \`playwright-cli install-browser ${channel}\` to install`);
-  else
-    throw new Error(`Browser "${channel}" is not installed. Run \`npx @playwright/mcp install-browser ${channel}\` to install`);
+    throw new Error(`${label} is not installed. Run \`playwright-cli install-browser ${target}\` to install`);
+  throw new Error(`${label} is not installed. Run \`npx @playwright/mcp install-browser ${target}\` to install`);
 }
diff --git a/tests/mcp/video.spec.ts b/tests/mcp/video.spec.ts
index 6481bdbb124db..79043bdb5f0e5 100644
--- a/tests/mcp/video.spec.ts
+++ b/tests/mcp/video.spec.ts
@@ -14,6 +14,8 @@
  * limitations under the License.
  */
 
+import fs from 'fs';
+
 import { test, expect } from './fixtures';
 import type { Client } from '@modelcontextprotocol/sdk/client/index.js';
 
@@ -60,6 +62,39 @@ async function closeBrowser(client: Client) {
   });
 }
 
+test('reports missing ffmpeg, not missing browser, when recordVideo is enabled', {
+  annotation: { type: 'issue', description: 'https://github.com/microsoft/playwright/issues/40862' },
+}, async ({ startClient, server, mcpBrowser }, testInfo) => {
+  test.skip(mcpBrowser !== 'chrome' && mcpBrowser !== 'msedge', 'Channel browsers use system-installed binaries; bundled browsers would also be missing under an empty PLAYWRIGHT_BROWSERS_PATH');
+
+  const emptyBrowsersPath = testInfo.outputPath('empty-browsers');
+  await fs.promises.mkdir(emptyBrowsersPath, { recursive: true });
+
+  const { client } = await startClient({
+    env: { PLAYWRIGHT_BROWSERS_PATH: emptyBrowsersPath },
+    config: {
+      browser: {
+        contextOptions: {
+          recordVideo: { dir: testInfo.outputPath('videos') },
+        },
+      },
+    },
+  });
+
+  const response = await client.callTool({
+    name: 'browser_navigate',
+    arguments: { url: server.HELLO_WORLD },
+  });
+  expect.soft(response).toHaveResponse({
+    isError: true,
+    error: expect.stringContaining('FFmpeg is not installed'),
+  });
+  expect.soft(response).toHaveResponse({
+    isError: true,
+    error: expect.not.stringContaining(`Browser "${mcpBrowser}" is not installed`),
+  });
+});
+
 async function produceFrames(client: Client) {
   expect(await client.callTool({
     name: 'browser_evaluate',