Firefox browser never connected (Cannot read properties of undefined (reading 'browsingContextGetTree'))

[CastiGiuseppe]

Current behavior

I'm trying to run tests on Firefox 136.0.3 with cypress version 14.2.0 on windows machine.
I have this error :

Timed out waiting for the browser to connect. Retrying...
Timed out waiting for the browser to connect. Retrying again...
The browser never connected. Something is wrong. The tests cannot run. Aborting...
The browser never connected. Something is wrong. The tests cannot run. Aborting...

Cannot read properties of undefined (reading 'browsingContextGetTree')
TypeError: Cannot read properties of undefined (reading 'browsingContextGetTree')
    at Object.connectToNewSpecBiDi (<embedded>:2764:205513)
    at Object.K (<embedded>:2770:9092)
    at Object.connectToNewSpec (<embedded>:2770:30156)
    at async v.relaunchBrowser (<embedded>:2879:3[86](https://git.vascloud.be/nihii/vidis-webcomponent-tests/-/jobs/509981#L86)03)

Desired behavior

Cypress should run tests on firefox.

Test code to reproduce

N/A

Cypress Version

14.2.0

Node version

22.12.0

Operating System

Windows 11 Entreprise 24H2

Debug Logs

Other

No response

[AtofStryker]

Hi @CastiGiuseppe. Thank you for opening an issue. I tried to reproduce this with https://github.com/AtofStryker/cypress_issue_31381 but was unable to reproduce. The only difference is I am on Windows 10 and not 11. Are you able to give further instruction on how to reproduce the error?

[MikeMcC399]

@CastiGiuseppe

Like @AtofStryker I was not able to reproduce this issue either and I am using Windows 11 24H2. Could you try the following test to see if it fails for you?

git clone https://github.com/cypress-io/github-action
cd github-action
cd examples/browser
npm ci
npm run cy:run:firefox

Logs

Here are the logs showing it working:

DevTools listening on ws://127.0.0.1:55265/devtools/browser/d8b8c3b8-d123-47dd-82fd-d7d5a0a45f29

====================================================================================================

  (Run Starting)

  ┌────────────────────────────────────────────────────────────────────────────────────────────────┐
  │ Cypress:        14.2.1                                                                         │
  │ Browser:        Firefox 136 (headless)                                                         │
  │ Node Version:   v22.12.0 (C:\Program Files\nodejs\node.exe)                                    │
  │ Specs:          1 found (spec.cy.js)                                                           │
  │ Searched:       cypress/e2e/**/*.cy.{js,jsx,ts,tsx}                                            │
  └────────────────────────────────────────────────────────────────────────────────────────────────┘


────────────────────────────────────────────────────────────────────────────────────────────────────

  Running:  spec.cy.js                                                                      (1 of 1)
before launching browser
{
  name: 'firefox',
  family: 'firefox',
  channel: 'stable',
  displayName: 'Firefox',
  version: '136.0.3',
  path: 'C:\\Program Files\\Mozilla Firefox\\firefox.exe',
  majorVersion: '136',
  isHeadless: true,
  isHeaded: false
}


top window inner w, h is 1173x660
  √ works (2175ms)

  1 passing (4s)


  (Results)

  ┌────────────────────────────────────────────────────────────────────────────────────────────────┐
  │ Tests:        1                                                                                │
  │ Passing:      1                                                                                │
  │ Failing:      0                                                                                │
  │ Pending:      0                                                                                │
  │ Skipped:      0                                                                                │
  │ Screenshots:  3                                                                                │
  │ Video:        false                                                                            │
  │ Duration:     3 seconds                                                                        │
  │ Spec Ran:     spec.cy.js                                                                       │
  └────────────────────────────────────────────────────────────────────────────────────────────────┘


  (Screenshots)

  -  C:\Users\mikem\AppData\Local\Temp\tmp.xXl5mayn5X\github-action\examples\browser\     (1280x720)
     cypress\screenshots\spec.cy.js\runner.png
  -  C:\Users\mikem\AppData\Local\Temp\tmp.xXl5mayn5X\github-action\examples\browser\     (1091x720)
     cypress\screenshots\spec.cy.js\viewport.png
  -  C:\Users\mikem\AppData\Local\Temp\tmp.xXl5mayn5X\github-action\examples\browser\    (1091x5328)
     cypress\screenshots\spec.cy.js\fullPage.png


====================================================================================================

  (Run Finished)


       Spec                                              Tests  Passing  Failing  Pending  Skipped
  ┌────────────────────────────────────────────────────────────────────────────────────────────────┐
  │ ✔  spec.cy.js                               00:03        1        1        -        -        - │
  └────────────────────────────────────────────────────────────────────────────────────────────────┘
    ✔  All specs passed!                        00:03        1        1        -        -        -

[CastiGiuseppe]

@MikeMcC399 I tried what you explained and it fails again.

Here is the log I have. I don't know if it can help you.

> > example-browser@1.1.0 cy:run:firefox
> cypress run --browser firefox

It looks like this is your first time using Cypress: 14.2.1

√  Verified Cypress! C:\Users\gica\AppData\Local\Cypress\Cache\14.2.1\Cypress

Opening Cypress...


DevTools listening on ws://127.0.0.1:58066/devtools/browser/a9357ede-0666-4819-b9a1-8a2eb7631015

====================================================================================================

  (Run Starting)

  ┌────────────────────────────────────────────────────────────────────────────────────────────────┐
  │ Cypress:        14.2.1                                                                         │
  │ Browser:        Firefox 136 (headless)                                                         │
  │ Node Version:   v22.12.0 (c:\dev\js\nodejs\node.exe)                                           │
  │ Specs:          1 found (spec.cy.js)                                                           │
  │ Searched:       cypress/e2e/**/*.cy.{js,jsx,ts,tsx}                                            │
  └────────────────────────────────────────────────────────────────────────────────────────────────┘


────────────────────────────────────────────────────────────────────────────────────────────────────

  Running:  spec.cy.js                                                                      (1 of 1)
before launching browser
{
  name: 'firefox',
  family: 'firefox',
  channel: 'stable',
  displayName: 'Firefox',
  version: '136.0.3',
  path: 'C:\\Program Files\\Mozilla Firefox\\firefox.exe',
  majorVersion: '136',
  isHeadless: true,
  isHeaded: false
}

Timed out waiting for the browser to connect. Retrying...
before launching browser
{
  name: 'firefox',
  family: 'firefox',
  channel: 'stable',
  displayName: 'Firefox',
  version: '136.0.3',
  path: 'C:\\Program Files\\Mozilla Firefox\\firefox.exe',
  majorVersion: '136',
  isHeadless: true,
  isHeaded: false
}

Timed out waiting for the browser to connect. Retrying again...
before launching browser
{
  name: 'firefox',
  family: 'firefox',
  channel: 'stable',
  displayName: 'Firefox',
  version: '136.0.3',
  path: 'C:\\Program Files\\Mozilla Firefox\\firefox.exe',
  majorVersion: '136',
  isHeadless: true,
  isHeaded: false
}
>
The browser never connected. Something is wrong. The tests cannot run. Aborting...

The browser never connected. Something is wrong. The tests cannot run. Aborting...

  (Results)

  ┌────────────────────────────────────────────────────────────────────────────────────────────────┐
  │ Tests:        0                                                                                │
  │ Passing:      0                                                                                │
  │ Failing:      1                                                                                │
  │ Pending:      0                                                                                │
  │ Skipped:      0                                                                                │
  │ Screenshots:  0                                                                                │
  │ Video:        false                                                                            │
  │ Duration:     0 seconds                                                                        │
  │ Spec Ran:     spec.cy.js                                                                       │
  └────────────────────────────────────────────────────────────────────────────────────────────────┘


====================================================================================================

  (Run Finished)


       Spec                                              Tests  Passing  Failing  Pending  Skipped
  ┌────────────────────────────────────────────────────────────────────────────────────────────────┐
  │ ×  spec.cy.js                                 0ms        -        -        1        -        - │
  └────────────────────────────────────────────────────────────────────────────────────────────────┘
    ×  1 of 1 failed (100%)                       0ms        -        -        1        -        -

[MikeMcC399]

@CastiGiuseppe

Thank you for testing with the example! This works for me on 2 different Windows 11 24H2 systems, so if it fails for you, then there is something different on your system / network.

Did you try uninstalling and re-installing Firefox?

Do you have access to a different Windows 11 system to try on that one?

Are you on a restricted corporate network?

[CastiGiuseppe]

I'm working on a restricted corporate network.

I will try uninstalling and re-installing Firefox.

I will keep you inform. Thanks

[MikeMcC399]

@CastiGiuseppe

I'm working on a restricted corporate network.

You may need to work with your network admin on this point and I'm wondering if Windows group policies may be causing your issue. I don't have in-depth experience with this, however you might want to try running:

GPRESULT /R

from a Windows cmd or PowerShell terminal to see if any relevant restrictions are shown.

[CastiGiuseppe]

I re-tried uninstalling and re-installing Firefox and I still have the issue.

[MikeMcC399]

@CastiGiuseppe

I re-tried uninstalling and re-installing Firefox and I still have the issue.

Re-installing was suggested as a precautionary measure. The outstanding points are:

• Is the problem reproducible on other Windows 11 systems in your environment?
• Does your network or your system have Windows Group Policies enabled that could affect how the Mozilla Firefox browser runs?

[CastiGiuseppe]

I did several tries (downgrading cypress & firefox version).

Fortunately it's working with cypress 14.2.1 & Firefox 137

Thanks for your time and help.

[MikeMcC399]

@CastiGiuseppe

It's good to hear that you have Cypress and Firefox working now. So thank you for reporting back! We don't have an explanation why it wasn't working before though it seems.

If you don't need any more help, then I suggest that you close this issue ⬇

[JoostK]

Also seeing this failure using the latest cypress/included:14.2.1 Docker image (which contains Firefox 136). The environment has restricted network access (effectively none, only connections to a very limited set of hosts are allowed, other connections are silently dropped during the TCP handshake) but it's unclear how to resolve this.

[MikeMcC399]

@JoostK

• If you are using a Cypress Docker image with Firefox in an air-gapped environment, I suggest you read Cypress tests fail in air-gapped network on Firefox cypress-docker-images#1298 (comment) which lists detailed workaround suggestions for slightly older versions.