How to solve "Failed to move to new namespace" Problem if --no-sandbox doesn't work

I want to add testing of my angular application to my build.

But I'm running into this error:

Failed to move to new namespace: PID namespaces supported, Network namespace > supported, but failed: errno = Operation not permitted

I tried adding --no-sandbox to the flags but sadly that didn't solve the issue for me.

This is my karma.conf.js:

module.exports = function (config) {
  config.set({
    customLaunchers: {
      ChromeHeadless: {
        base: 'ChromiumHeadless',
        flags: [
          '--headless',
          '--no-sandbox',
          '--disable-gpu',
          '--remote-debuging-port=9222'
        ],
      }
    },
    basePath: '',
    frameworks: ['jasmine', '@angular-devkit/build-angular'],
    plugins: [
      require('karma-jasmine'),
      require('karma-chrome-launcher'),
      require('karma-jasmine-html-reporter'),
      require('karma-coverage-istanbul-reporter'),
      require('@angular-devkit/build-angular/plugins/karma')
    ],
    client:{
      clearContext: false // leave Jasmine Spec Runner output visible in browser
    },
    coverageIstanbulReporter: {
      dir: require('path').join(__dirname, 'coverage'), reports: [ 'html', 'lcovonly' ],
      fixWebpackSourcePaths: true
    },
    angularCli: {
      environment: 'dev'
    },
    reporters: ['progress', 'kjhtml'],
    port: 9876,
    colors: true,
    logLevel: config.LOG_INFO,
    autoWatch: false,
    browsers: ['ChromiumHeadless'],
    singleRun: true
  });
};

How do I get arround this problem?