I am currently unable to run my Kernel tests on my server. I am running the test from within the Drupal UI but they error out with:
"PHPunit Test failed to complete; Error:"
with a log messages of
Notice: Undefined index: error in Drupal\simpletest\Form\SimpletestResultsForm::addResultForm()
The file public://simpletest/verbose was not deleted because it does not exist.