Protractor does not run after installation

Question

After installation npm i protractor -g and running webdriver-manager update as in Tutorial, the next command webdriver-manager start throws errors:

$ webdriver-manager start
seleniumProcess.pid: 63737
Exception in thread "main" java.lang.UnsupportedClassVersionError: org/openqa/grid/selenium/GridLauncher : Unsupported major.minor version 51.0
    at java.lang.ClassLoader.defineClass1(Native Method)
    at java.lang.ClassLoader.defineClass(ClassLoader.java:700)
    at java.security.SecureClassLoader.defineClass(SecureClassLoader.java:124)
    at java.net.URLClassLoader.defineClass(URLClassLoader.java:260)
    at java.net.URLClassLoader.access$000(URLClassLoader.java:56)
    at java.net.URLClassLoader$1.run(URLClassLoader.java:195)
    at java.security.AccessController.doPrivileged(Native Method)
    at java.net.URLClassLoader.findClass(URLClassLoader.java:188)
    at java.lang.ClassLoader.loadClass(ClassLoader.java:319)
    at sun.misc.Launcher$AppClassLoader.loadClass(Launcher.java:330)
    at java.lang.ClassLoader.loadClass(ClassLoader.java:254)
    at java.lang.ClassLoader.loadClassInternal(ClassLoader.java:399)
Selenium Standalone has exited with code 1

Here the installation output:

npm i protractor -g

> bufferutil@1.2.1 install /usr/local/lib/node_modules/protractor/node_modules/selenium-webdriver/node_modules/ws/node_modules/bufferutil
> node-gyp rebuild

child_process: customFds option is deprecated, use stdio instead.
No receipt for 'com.apple.pkg.CLTools_Executables' found at '/'.

No receipt for 'com.apple.pkg.DeveloperToolsCLILeo' found at '/'.

  CXX(target) Release/obj.target/bufferutil/src/bufferutil.o
  SOLINK_MODULE(target) Release/bufferutil.node
  SOLINK_MODULE(target) Release/bufferutil.node: Finished

> utf-8-validate@1.2.1 install /usr/local/lib/node_modules/protractor/node_modules/selenium-webdriver/node_modules/ws/node_modules/utf-8-validate
> node-gyp rebuild

child_process: customFds option is deprecated, use stdio instead.
No receipt for 'com.apple.pkg.CLTools_Executables' found at '/'.

No receipt for 'com.apple.pkg.DeveloperToolsCLILeo' found at '/'.

  CXX(target) Release/obj.target/validation/src/validation.o
  SOLINK_MODULE(target) Release/validation.node
  SOLINK_MODULE(target) Release/validation.node: Finished
/usr/local/bin/protractor -> /usr/local/lib/node_modules/protractor/bin/protractor
/usr/local/bin/webdriver-manager -> /usr/local/lib/node_modules/protractor/bin/webdriver-manager
protractor@2.5.1 /usr/local/lib/node_modules/protractor
├── jasminewd@1.1.0
├── jasminewd2@0.0.6
├── html-entities@1.1.3
├── q@1.0.0
├── minijasminenode@1.1.1
├── adm-zip@0.4.4
├── optimist@0.6.1 (wordwrap@0.0.3, minimist@0.0.10)
├── jasmine@2.3.2 (exit@0.1.2, jasmine-core@2.3.4)
├── glob@3.2.11 (inherits@2.0.1, minimatch@0.3.0)
├── saucelabs@1.0.1 (https-proxy-agent@1.0.0)
├── accessibility-developer-tools@2.6.0
├── source-map-support@0.2.10 (source-map@0.1.32)
├── lodash@2.4.2
├── request@2.57.0 (caseless@0.10.0, aws-sign2@0.5.0, forever-agent@0.6.1, stringstream@0.0.5, tunnel-agent@0.4.1, oauth-sign@0.8.0, isstream@0.1.2, json-stringify-safe@5.0.1, node-uuid@1.4.7, combined-stream@1.0.5, qs@3.1.0, form-data@0.2.0, mime-types@2.0.14, tough-cookie@2.2.1, http-signature@0.11.0, bl@0.9.4, har-validator@1.8.0, hawk@2.3.1)
└── selenium-webdriver@2.47.0 (tmp@0.0.24, rimraf@2.4.3, xml2js@0.4.4, ws@0.8.0)