Push test hung up after test completion

I have grunt tasks configured to start the protractor web relay and then run the protractor tests with the protractor runner, the grunt configuration is like

    .....
    protractor_webdriver: {
        start: {
            options: {
                path: 'node_modules/protractor/bin/',
                command: 'webdriver-manager start --standalone'
            }
        }
    },
    protractor: {
        options: {
            configFile: proctatorConf,
            noColor: false,
            args: {
            }
        },
        auto: {
            options: {
                keepAlive: true,
                args: {
                }
            }
        },
        singlerun: {
            options: {
                keepAlive: false,
                args: {
                }
            }
        }
    }
    ....
    grunt.registerTask('test:e2e', [
      'shell:update_webdriver',
      'protractor_webdriver:start',
      'protractor:singlerun'
    ]);

      

        
        
        
      

    

and in Jenkins I installed the xvfb-plugin and said in the job config to start the Xvfb screen and shutdown after shutdown,

And what is the problem, when the jenkins command is executing the command grunt test:e2e

, it does the whole test, gives me the crash information like

Finished in 16.455 seconds [31m4 tests, 6 assertions, 4 failures

and jenkins worked depended on it, what could be the problem for this?