Saucelabs: org.openqa.selenium.WebDriverException: Test with session id *** has already completed and cannot receive further commands

When I run test cases in parallel, I get a lot of "Test has already completed errors". I'm pretty sure the following is not the reason, as mentioned in the General error messages here .

• driver.quit () is not the reason for the test to be marked complete, as it doesn't even run when the above error occurs.

• we have always managed to ensure that the number of simultaneous virtual machine starts is less than the total number of virtual machines available for the account.

• The internet connection is strong and stable.

Can you help with this question to determine what is wrong?