Karma can no longer be executed outside angular, so I am getting this error:

Error: The '@angular-devkit/build-angular/plugins/karma' karma plugin is meant to be used from within Angular CLI and will not work correctly outside of it

after changing the location of Karma as required in newer versions of angular

Recommandations is to use a command like

ng test --karma-config karma.somestuff.conf.js

to run Karma, but I can't find any samples of how to do that from an express server like the one you have created for calling Karma