[BUG]: Mock issue on Playwright 1.49+ using MPTS

[hcura-qa]

Describe the bug
After the Playwright update to version 1.49.0 (also tested with 1.49.1), the native Playwright mocking tool (route()) is not working anymore when running using Microsoft Playwright Testing service (MPTS).

The test using a mocked call is failing with the following error:

Error: Socks5 proxy rejected connection - ConnectionRefused
Call log:
  - → POST <undisclosed>
    - user-agent: Mozilla/5.0 (Windows NT 10.0; Win64; x64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/131.0.6778.33 Safari/537.36
    - accept: application/json, text/plain, */*
    - accept-encoding: gzip,deflate,br
    - accept-language: en-US
    - content-type: application/json
    - cookie: <undisclosed>
    - origin: <undisclosed>
    - referer: <undisclosed>
    - sec-ch-ua: "HeadlessChrome";v="131", "Chromium";v="131", "Not_A Brand";v="24"
    - sec-ch-ua-mobile: ?0
    - sec-ch-ua-platform: "Windows"
    - content-length: 93

We suspect the issue might be caused with the recent architecture change related to Chromium headless, that can be found here: microsoft/playwright#33566

To Reproduce
Steps to reproduce the behavior:

1. Run a test with a mocked call (using route() Playwright's native method)
2. Perform a route.fetch() - reproducible with our app so far
3. Observe

Screenshots
N/A

Setup information (please complete the following information):

• Session Id: 82601638-f67d-4a8c-95bb-dc2db38b6a2d
• Browser on which tests are executed: Chromium
• Playwright Version: 1.49+
• Client machine OS: Linux
• OS requested on Service: Linux

Additional context
The affected test has no issues when running against our Github runners infrastructure. This is a 100% reproducible issue using Microsoft Playwright Testing Service.

[manikanta-addagatla]

Hi,
We couldn't reproduce this issue from our end. Tried with simple test using route() and test has passed.

Could you please provide a sample to repro the issue?

[hcura-qa]

I've implemented a test with similar steps, but the issue is not happening here (sessionId 074d7a6b-906e-4d85-b5f1-5f7109290f31):

  test('generic mock test', async ({ page }) => {
    const searchString = 'hcura-qa';
    const mockedName = 'Mocked Name';

    await page.goto('https://gh-users-search.netlify.app/');
    await page.route(`*/**/users/${searchString}`, async (route) => {
      const response = await route.fetch();
      let body = await response.json();

      body.name = mockedName;

      await route.fulfill({
        status: 200,
        body: JSON.stringify(body),
      });
    });

    await page.getByTestId('search-bar').fill(searchString);
    await page.getByRole('button', { name: 'search' }).click();
    await expect(page.getByRole('heading', { name: mockedName, level: 4 })).toBeVisible();
  });

For us, when running our app using MPT service under CI, the referred failure is happening on line "const response = await route.fetch();".

It is not happening when using our infrastructure (github runners), and it happens when running over MPT service, with Playwright 1.49+, and it is not reproducible locally, that's why we think the issue is likely related to MPT.

[Sid200026]

Hi @hcura-qa, from the initial error message shared, I see that the User-Agent indicates Windows operating system while you had mentioned that the client OS is Linux. I'm assuming you are running tests using some proxy server which is running on Windows.

- user-agent: Mozilla/5.0 (Windows NT 10.0; Win64; x64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/131.0.6778.33 Safari/537.36
- sec-ch-ua-platform: "Windows"

Could you provide us with the below details which would help us investigate the issue further

• The previous version in which your test was working with Microsoft Playwright Testing Service
• Node version
• Playwright configuration file
• If you are using some http proxy or socksv5 in your tests
• Client-side channel logs (Channel logs might contain some secrets like url, auth tokens, etc. Feel free to remove them before sending the logs)
  • You can get them by setting the environment variable DEBUG=pw:channel*
  • You can send this via email to playwrighttesting@microsoft.com

[puagarwa]

HI @hcura-qa , Gentle reminder if you got chance to look into above info.

[miguelofbc]

@puagarwa @Sid200026 We’ve successfully replicated the failure, but it’s now blocking an important initiative. @hcura-qa has already reached out to the suggested contact via email. Could you please take a look at this as soon as possible? If the logs we’re sharing aren’t sufficient to identify the issue, feel free to schedule time tomorrow for further debugging.

[miguelofbc]

Hello @puagarwa @Sid200026,

This issue appears to be a regression in Playwright 1.49.1. It works as expected in version 1.48.2 but fails in both 1.49.1 and 1.50.0.

Could you please share an ETA for the fix?

Sent some more details on email thread, but here it is the stack trace for the failure if it helps to get this issue fixed.

Failing Logs (Playwright 1.49.1):

pw:socks [1adac760240d34ad3b591e21a9882973] <= connect error ECONNREFUSED
pw:channel <EVENT {"guid":"jsonPipe@46fd59359b8b3d476e774013ee0ebc12","method":"message","params":{"message":{"id":9,"error":{"error":{"message":"Socks5 proxy rejected connection - ConnectionRefused","stack":"Error: Socks5 proxy rejected connection - ConnectionRefused\n    at t.closeSocket (/usr/src/app/Workers/BrowserPodWorker/mpt-playwright-server-1_49/node_modules/playwright-core/lib/utilsBundleImpl/index.js:35:72542)\n    at t.handleSocks5FinalHandshakeResponse (/usr/src/app/Workers/BrowserPodWorker/mpt-playwright-server-1_49/node_modules/playwright-core/lib/utilsBundleImpl/index.js:35:78259)\n    at t.processData (/usr/src/app/Workers/BrowserPodWorker/mpt-playwright-server-1_49/node_modules/playwright-core/lib/utilsBundleImpl/index.js:35:71735)\n    at t.onDataReceivedHandler (/usr/src/app/Workers/BrowserPodWorker/mpt-playwright-server-1_49/node_modules/playwright-core/lib/utilsBundleImpl/index.js:35:71205)\n    at Socket.onDataReceived (/usr/src/app/Workers/BrowserPodWorker/mpt-playwright-server-1_49/node_modules/playwright-core/lib/utilsBundleImpl/index.js:35:69600)\n    at Socket.emit (node:events:514:28)\n    at addChunk (node:internal/streams/readable:324:12)\n    at readableAddChunk (node:internal/streams/readable:297:9)\n    at Readable.push (node:internal/streams/readable:234:10)\n    at TCP.onStreamRead (node:internal/stream_base_commons:190:23)","name":"Error"}},"log":["  - → POST http://localhost:4000/rpc","    - user-agent: Mozilla/5.0 (Windows NT 10.0; Win64; x64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/131.0.6778.33 Safari/537.36","    - accept: */*","    - accept-encoding: gzip,deflate,br","    - Content-Type: application/json","    - content-length: 136","    - cookie: session=TOKEN"]}}}
pw:channel <RECV {"id":9,"error":{"error":{"message":"Socks5 proxy rejected connection - ConnectionRefused","stack":"Error: Socks5 proxy rejected connection - ConnectionRefused\n    at t.closeSocket (/usr/src/app/Workers/BrowserPodWorker/mpt-playwright-server-1_49/node_modules/playwright-core/lib/utilsBundleImpl/index.js:35:72542)\n    at t.handleSocks5FinalHandshakeResponse (/usr/src/app/Workers/BrowserPodWorker/mpt-playwright-server-1_49/node_modules/playwright-core/lib/utilsBundleImpl/index.js:35:78259)\n    at t.processData (/usr/src/app/Workers/BrowserPodWorker/mpt-playwright-server-1_49/node_modules/playwright-core/lib/utilsBundleImpl/index.js:35:71735)\n    at t.onDataReceivedHandler (/usr/src/app/Workers/BrowserPodWorker/mpt-playwright-server-1_49/node_modules/playwright-core/lib/utilsBundleImpl/index.js:35:71205)\n    at Socket.onDataReceived (/usr/src/app/Workers/BrowserPodWorker/mpt-playwright-server-1_49/node_modules/playwright-core/lib/utilsBundleImpl/index.js:35:69600)\n    at Socket.emit (node:events:514:28)\n    at addChunk (node:internal/streams/readable:324:12)\n    at readableAddChunk (node:internal/streams/readable:297:9)\n    at Readable.push (node:internal/streams/readable:234:10)\n    at TCP.onStreamRead (node:internal/stream_base_commons:190:23)","name":"Error"}},"log":["  - → POST http://localhost:4000/rpc","    - user-agent: Mozilla/5.0 (Windows NT 10.0; Win64; x64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/131.0.6778.33 Safari/537.36","    - accept: */*","    - accept-encoding: gzip,deflate,br","    - Content-Type: application/json","    - content-length: 136","    - cookie: session=TOKEN"]}

[puagarwa]

Hi @miguelofbc , We have identified the fix and its already available in alpha version to try out. Fix will be ported onto 1.50 and will be available early next week.

[miguelofbc]

Hello @puagarwa

Thanks for following up, that is good news! It seems to be passing now with "@playwright/test": "^1.51.0-alpha-2025-01-30". Could you please point me to the link for the PR with the fix?
So, the plan is to release playwright 1.50.1 next week to include the fix for this, is that correct?

[puagarwa]

This is revert PR Revert "Reapply "fix(har timing): record connect timing for proxied connections" (#32855) (#33003)" by dgozman · Pull Request #34535 · microsoft/playwright which fixed the issue.

That’s correct. I will update you once 1.50.1 get released and service browsers get updated with patched version.

[puagarwa]

Hi @miguelofbc ,
The issue is fixed in 1.50.1, please let us know if you face any issue.