package.json must be actual JSON, not just JavaScript

Question

I used http://jsonlint.com/ to check the syntax for this package.json file

{
  "name": "hello-world",
  "description": "hello world test app",
  "version": "0.0.1",
  "private": true,
  "dependencies": {
    "express": “4.6.1"
  }
}

it returns the error

Parse error on line 7:
...        "express": “4.6.1"  }}
----------------------^
Expecting 'STRING', 'NUMBER', 'NULL', 'TRUE', 'FALSE', '{', '['

not sure what is wrong with this. terminal is throwing the error for using npm install

"Failed to parse package.json data.
npm ERR! package.json must be actual JSON, not just JavaScript."

Answer 1

Just type npm cache clean on prompt and all the things must to work again.