Intermittent 411 error for AJAX call on different browsers-CodePudding

I have an older C# MVC 4.7 web app that has a specific $.post call. Running locally from Visual Studio 2019 in any browser, I have no problem at all. The call goes through and posts the partial page to the div as expected. Running from our test URL, it gives me an error in Edge and Chrome, but not in Firefox. It returns a 411 error, which I know means it's a content length issue. The problem is that others accessing the site do not run across that issue in any browser. Since it works on others' machines and on one particular browser on my local machine, I suspect it's a security setting or something along those lines for that particular site. I've cleared out the settings, reset to factory default, removed extensions, assured that's up-to-date and tested it with and without antivirus software interaction.

This fails:

$.post('/Controller/Method', function (data) {
                $('#container').html(data);
            });

But this works:

$.post("/Controller/OtherMethod", { paramOne: varOne, paramTwo: varTwo }, function (data) {

                    $("#container").html(data);

                });

Both functions work in Firefox when running from the test URL, only second one works in Edge/Chrome from test URL.

Any ideas on what I might need to check?

Here's the header from the failing call in Dev Tools:

General

Request URL: https://[url]/Controller/Method?param=123

Request Method: POST

Status Code: 411

Remote Address: [remote_ip]

Referrer Policy: strict-origin-when-cross-origin

Response Headers

content-type: text/html; charset=us-ascii

date: Thu, 19 Aug 2021 17:08:18 GMT

server: Microsoft-HTTPAPI/2.0

Request Headers

:authority: [url]

:method: POST

:path: Controller/Method?param=123

:scheme: https

accept: /

accept-encoding: gzip, deflate, br

accept-language: en-US,en;q=0.9

cache-control: no-cache

content-length: 0

cookie: [cookie info]

origin: https://[url]

pragma: no-cache

referer: https://[url]/Controller/Method?param=123

sec-ch-ua: "Chromium";v="92", " Not A;Brand";v="99", "Google Chrome";v="92"

sec-ch-ua-mobile: ?0

sec-fetch-dest: empty

sec-fetch-mode: cors

sec-fetch-site: same-origin

user-agent: Mozilla/5.0 (Windows NT 10.0; Win64; x64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/92.0.4515.159 Safari/537.36

x-requested-with: XMLHttpRequest

CodePudding user response：

After experiencing the same problem in both Chrome and Edge across two different websites, I think I have the answer:

The problem appears to be BitDefender antivirus.

If I disable BitDefender protection, the post requests succeed.

EDIT: Bizarrely, if I then re-enable BitDefender protection, the issue doesn't come back.

After stumbling across the solution, I found a few references to people having the same problem: https://community.bitdefender.com/en/discussion/88573/status-411-length-required-during-browsing https://support.mozilla.org/en-US/questions/1344632