The target is to run tests in 2 browsers, the test script should be modified. What was done: if (Cypress.isBrowser('chrome') & Cypress.isBrowser('firefox')), as results test is running, but in default browser, what is electron or it depends what is selected browser in cypress runner. I have 3 browsers now. I did ./node_modules/.bin/cypress run --browser chrome this works, but unfortunately looks like it's impossible to ./node_modules/.bin/cypress run --browser chrome and ./node_modules/.bin/cypress run --browser Firefox. Also I added script in package .json file - "cypress-multi-browsers": "npm run unified-cypress-dev -- --browser firefox & npm run unified-cypress-dev -- --browser chrome", but getting errors about Firefox security.