cypress: Cypress cannot access different ports on localhost

Current behavior

A similar issue has been closed previously (https://github.com/cypress-io/cypress/issues/6475) without a working solution in place.

I am trying to implement e2e tests for a web application with an AngularJS frontend and a Django backend with Cypress. Both run locally (frontend: localhost:4200, backend: localhost:8000), but either one or the other are not accessible in the Cypress environment, despite working perfectly fine in a regular browser window. This is happening regardless of which (Cypress) browser I am using. In each case, the domain I access first manages to load with the other being blocked:

Desired behavior

Cypress should be able to reach both ports on localhost

Test code to reproduce

The code for both backend and frontend are available at https://github.com/ChriReiter/JAM The running config uses an external database server, which is no longer in use. To redirect requests to the localhost, change the file at frontend/src/environments/environments.ts to target the localhost as the apiBaseUrl

Cypress Version

12.8.1

Node version

18.12.0

Operating System

Windows 11, Version 22H2

Debug Logs

cy.visit() failed trying to load:



http://localhost:4200/



We attempted to make an http request to this URL but the request failed without a response.



We received this error at the network level:



  > Error: connect ECONNREFUSED 127.0.0.1:4200



Common situations why this would fail:

  - you don't have internet access

  - you forgot to run / boot your web server

  - your web server isn't accessible

  - you have weird network configuration settings on your computer
cypress/e2e/spec.cy.ts:5:6
  3 | })
  4 | it('passes', () => {
> 5 |   cy.visit('http://localhost:4200/')
    |      ^
  6 | })
  7 |  
View stack trace
 Print to console
    at <unknown> (http://localhost:8000/__cypress/runner/cypress_runner.js:138252:82)
    at visitFailedByErr (http://localhost:8000/__cypress/runner/cypress_runner.js:137644:12)
    at <unknown> (http://localhost:8000/__cypress/runner/cypress_runner.js:138251:11)
From previous event:
    at visit (http://localhost:8000/__cypress/runner/cypress_runner.js:138217:17)
    at Context.visit (http://localhost:8000/__cypress/runner/cypress_runner.js:138268:14)
    at wrapped (http://localhost:8000/__cypress/runner/cypress_runner.js:151174:43)
From Your Spec Code:
    at Context.eval (webpack:///./cypress/e2e/spec.cy.ts:5:5)
From Node.js Internals:
  Error: connect ECONNREFUSED 127.0.0.1:4200
      at TCPConnectWrap.afterConnect [as oncomplete] (node:net:1187:16)

Other

No response