Google Storage ArgumentException when setting CORS config

I got the same error when I tried to set the CORS settings with the trailing comma "," as shown below:

[
    {
      "origin": ["http://localhost:8000"],
      "method": ["GET"],
      "responseHeader": ["Content-Type"],
      "maxAgeSeconds": 3600, 
    }                   // ↑ Trailing comma
]                          

So, I removed the trailing comma "," as shown below then I could set the CORS settings successfully without no error:

[
    {
      "origin": ["http://localhost:8000"],
      "method": ["GET"],
      "responseHeader": ["Content-Type"],
      "maxAgeSeconds": 3600 
    }                   // ↑ No trailing comma
]                          

after so many tries, I ended up with modifing json file to:

$ cat cors-json-file.json 
[{
    "origin": ["*"],
    "method": ["GET"],
    "maxAgeSeconds": 3600
}]

and... it worked! Note that example from Google documentation is my first case (with [{ on 2 lines)

I had the same problem and it was caused by the type of quotes used. By opening the json-file in a plain text editor and change the quote to standard ones fixed the problem.