I installed protractor following this tutorial and when i use webdriver-manager update it says:
selenium standalone is up to date.
chromedriver is up to date.
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In my case it was the due to damaged chromedriver zip file.
I have done following things to resolve this problem.
Downloaded chromedriver zip from ChromeDriver Download Page
Extracted that zip file at "node_modules\protractor\selenium\" (i.e. Copied "chromedriver.exe" to this location)
Then it started working as expected. Hope this will help you.