Flying Grizzly's HTML Form Submission Error

Problem

I would like to submit Flying Grizzly’s form. I filled in every blanks and then I clicked the “submit” button below. I was greeted with a MISSING_REQUIRED_FIELDS error within a second.

{
    "success":false,
    "data":["replying_to"],
    "rawError":{
        "_smErrorCode":"MISSING_REQUIRED_FIELDS",
        "data":["replying_to"]
    },
    "errorCode":"MISSING_REQUIRED_FIELDS"
}

Discussion

The error code suggested that the form fields sent should be inspected.

1. Open the Web Developer Tools of your web browser. (press <F12>)
2. Select Network tab.
3. Click on the entry “500”, which represents an internal server error.
4. In the Params side pane, observe that fields[replying_to] has empty value. This is the source of error.

Solution

Right click on any element of the HTML form and select Inspect element. Under

<input id="comment_parent" name="fields[replying_to]" value="" type="hidden">

inject whatever you like, then click “submit” again.

Result

The error disappeared. After submission, I was redirected to the page. The HTTP status code “302” represented a redirection.