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Why do I have a message about "mxpnl.net" always in my Google Chrome console?

VM2335:34152 POST https://cr-input.mxpnl.net/data?_channel_id=&_partner_id=39571&_sub_id=0000&_app_version=1.0.23&_app=cs-dca net::ERR_INTERNET_DISCONNECTED

From what I can find, it appears to be a behaviour and analytic tracking script most likely related to mixpanel.com. I've recently run into the same thing, and followed it back to the content.js file inside the Tampermonkey chrome extension. I'm sure there are other chrome extensions that do the same thing, but uninstalling this chrome extension made the https://cr-input.mxpnl.net request stop.
I've also heard others have solved this problem by uninstalling Hide my adBlocker, but I can't confirm this myself.

This could mean you have a malicious Chrome extension installed. I googled "cr-input mxpnl" and came across this Google Forums post. If your internet is disconnected, the extension is probably failing to connect to the website where it wants to send your data.
To be clear, this is a guess. It may be a totally legit extension. However it would definitely be worth checking what extensions are installed, removing any that you don't recognise and doing a virus scan.

Since you are using some Adblocker extension that's the reason for getting
ERR_INTERNET_DISCONNECTED from the console. In the preferences of your Adblocker, you have blocked the access to Site Analytics Tracker
Turning off or Disabling the Web Statistic Tracker options from the preferences of the installed extension came from the Tampermonkey chrome extension. That alone stops accessing analytic tracking script most likely related to mixpanel.com.
There are other options from the preferences from the extension that might not be needed
Cheap Flights Advisor
PromoBar
Aliradar
So try to disable these options and always try to block all unencrypted requests by using HTTPS Everywhere extensions so that your information might not be stolen to any third party agents.

Google tag manager error with anonymous function

I have a issue after integration Google-tag-manager code to my web site: "GET https://www.googletagmanager.com/gtm.js?id=GTM-XXXXXX (index):336(anonymous function) (index):336(anonymous function)".
We suppose it is related that this script is not directly specified https protocol, and therefore the browser interprets the request as unsafe. This issue happend only Google Chrome. On FireFox everything ok. How it can be fixed?
I have read that issue can occur due to AdBlock, but when I off if, issue wasn't resolved.

As stated in Setup and installation you may try to verify or troubleshoot your installation with:
Tag Manager's Preview Mode
Tag Assistant Chrome extension

Chrome blocking iframe requests as cross-origin request even when origins are the same

This one has me stumped.
I have a web app that has a file upload/download area. Files are downloaded in the background via a temporary iFrame element. This is a single-paged AJAX application and the UI is written in Javascript, jQuery and uses the jQuery.FileDownloader.js to manage the iFrame. The application runs over HTTPS and the site and download URL are on the same exact domain. The back-end is a RESTful application. This has worked great for months. Until today.
All of a sudden, when attempting to download a file in Chrome, the browser reports an error of "Blocked a frame with origin https://example.com from accessing a cross-origin frame."
The problem is that the origin of the main site and that of the iframe are the exact same domain. I have ensured that the domains are the same as well as the protocol. Chrome is the only browser that throws up the cross-origin error. IE, Firefox, Opera, Safari... all work as expected. It's only in Chrome and it's only as of today. To make things worse, no updates were made to the browser. It truly is spontaneous. I've also ruled out plugins as the cause by running in Incognito mode, where none are allowed to run by my settings, as well as disabling my anti-virus software. This problem is being exhibited on other computers, in other locations (not on our LAN or subnet), all running Chrome.
And, again, both domains of the parent frame and the embedded iframe are identical. This only happens against the production server which runs over HTTPS. Other non-HTTPS sites (e.g. our dev environment, localhost) don't have the problem. Our SSL is valid. Since this is a single-paged AJAX application, we're trying to avoid popping up another window for the download.
Hopefully, someone can offer some advice. Thanks in advance.
Update: After additional research, I have found the solution to this problem is to enclose the filename in the response header in double-quotes.

I have found the cause of the problem. It turns out that Google Chrome has problems with files that have commas in their filename. When downloading the file via a direct link, Chrome will report that duplicate headers were reported from the server. This has been a long-standing problem with Chrome that has gone un-addressed. Other browsers are not susceptible to this problem. Still, it's a fairly easy problem to troubleshoot and, indeed, when I searched on this error, the first search result had the solution: remove commas from filenames when handling a request from Google Chrome.
However, this wasn't a direct link, it was an AJAX-request, which results in a different exception. In this case, the error provided by Chrome is the cross-origin request exception and this is what made it so difficult to troubleshoot.
So, the tl;dr of it all is to strip out commas in the names of uploaded files.

Another instance I found where this issue occurred is after executing code similar to:
document.domain = '[the exact same domain that the iframe originally had]'
Removing this line of code got rid of this error for me.

No 'Access-Control-Allow-Origin' header - Same Domain?

Today I attempted to browse a new feature recently deployed to our testing environment (NOT LOCAL). After navigating to the new feature I was met with a blank page. Confused, I checked Chrome's console and found an error:
XMLHttpRequest cannot load https://test.mytestsite.com/SomeApplication/api/SomeController/SomeMethod/8?Id=523283&SecondId=1612w3426653.
No 'Access-Control-Allow-Origin' header is present on the requested resource. Origin 'http://test.mytestsite.com' is therefore not allowed access.
This code makes an ajax call to a WebAPI (on the same domain) to retrieve some information on document.Ready. I understand the error and I'm familiar with it's typical cause. However, this call is being made from within the same domain AND it works for the other developers on my team.
Symptoms:
- Does not work for IE or Chrome/Incognito
- Does work for FireFox
- Works on all browsers for at least 4 other developers on the same domain that I reside on. (Indicating to me that this is an environmental issue)
Possible causes:
- I was doing some CORS research several weeks ago and perhaps I configured some Windows 7 setting to cause this to happen?
Google is saturated with the standard CORS issues, so I'm asking here and hopefully someone can help.

The issue at hand was due to inconsistencies between environments.
In our production environment SSL is enforced with a redirect in IIS, while in our testing environment it is not. I was navigating to the site via a bookmark using http. Updating the bookmark, as #epascarello suggested, fixed the problem.

WebSocket on IE10 giving a SecurityError

I am currently developing a website under IE10 (on Windows 8), using WebSockets in JavaScript. It runs fine under Firefox 18 and Chrome 25, but on IE10 I get a SecurityError when I establish the connection.
What I am doing seems pretty straghtforward :
websocket = new WebSocket('wss://hello.dev.mydomain.net');
But IE doesn't like it :
SCRIPT5022: SecurityError
The script is on "https://test.dev.mydomain.net" (not the real address obviously).
What bothers me is that if I just double-click the file on my local computer (e.g. file://...) it just works. Even worse: if I use fiddler to monitor HTTP traffic... it also works. Whereas there seems to be no connection at all without fiddler, as detailed in the API's specs. (See below.)
Judging by websocket spec, the exception should also appear on Chrome/Firefox... but it does not. So I doubt it has anything related to HTTP/HTTPS. In any case, I am using a wsS socket on a httpS page... Moreover: when I replace the wss address by another valid server found on an online example, it works.
I don't know if this is relevant, but the IP from test.dev.mydomain.net is 10.14.x.x where hello.dev.mydomain.net is 194.247.x.x. I don't know if it could trigger some kind of security on IE only...
One more thing: I have a certificate for *.dev.mydomain.net, IE does not seems to have problems with it. The script originally resides on a server called my.name.dev.mydomain.net, but since I am accessing it from another URL (I got a redirect since we first thought it could have been some kind of Same Origin Policy issue), I don't see how it could matter. At least I hope it does not...
Any idea is welcomed.
EDIT: adding the sites to the trusted zone does not work either.

It looks like IE throws a SecurityError if you're trying to open a websocket on a local (intranet) domain. To overcome this, you may disable IE's automatic algorithm for recognizing local sites. This can be done in Tools > Internet Options > Security > Local Intranet > Sites.
Uncheck all checkboxes (or only a particular one, if you know how exactly your domain did end up in intranet ones).
Note that IE uses (among other things) its proxy settings to determine local sites: if your domain is listed as excluded from proxying in proxy settings, then it will probably be treated as intranet one. This is why WebSockets work if you enable Fiddler: it modifies IE proxy settings and thus the list of intranet sites changes.

I had this problem in Windows7/IE11 after applying a security patch. For Windows10/Edge is the same story.
As this is a local websocket (ws://localhost) you have to add ws:\\localhost\ to Internet Explorer configurations (Tools > Internet Options > Security > Local Intranet > Sites > Advanced).
In Windows 10/Microsoft Edge you will find this configuration in Control Panel > Internet Options.
UPDATE
The address of your webapp (https://test.dev.mydomain.net) must be added to the local intranet zone too. Note that in the image the webapp address should be added.

Well, my question wasn't that successful, so I'll post the "workaround" I found.
I got another address for the website, in 194.247.. too. This, magically, solved it. Guess IE doesn't like mixing local and external stuff and watches the IP.
Anyways, I hope this may come in handy to anyone who's got the same issue.
If you have a solution to solve the "real" issue by configuring IE, let me know :)
Cheers,

Browsers has a websocket limitation. For example Internet Explorer has default limit of websocket connections set to 6 per host header name. the same limitation is set for WinForms WebBrowser component.
The solution is to add values under key Computer\HKEY_LOCAL_MACHINE\SOFTWARE\WOW6432Node\Microsoft\Internet Explorer\Main\FeatureControl\FEATURE_WEBSOCKET_MAXCONNECTIONSPERSERVER in registry. Just add DWORD value with executable name , for example iexplore.exe (or your application executable name if you use Web browser component) and set value from range 2..128
Second option how to solve SecurityException is to create multiple subdomains.

The client hostname/IP Address should be same as server IP/Hostname thats listening to otherwise you would get the above error.
1) Make sure whether server hostname configured to listen at IP/localhost etc andif not explicitly specify the hostname ast server
2) use the same hostname in the client. THis will solve the issue. It worked for me...

I encountered the error (although it did not say the SCRIPT5022 part, rather it just reports "ScriptError"). I got around the issue by clicking on "Trusted Sites" and then adding the machine hosting the remote websocket. Note, to add to trusted sites,
I had to supply the address without the "ws://" part (like just mymahcine.mydomain.com)
I had to uncheck the box that says "Require server verification https:// " option.
After I was done adding the domain, I re-checked the box "Require server verification (https://). I would recommend everyone to do the same. Unchecking the box is only a workaround to add sites that don't begin with https (rather ws:// in my case)

I had the same issue at one of my customer's environment.
It turned out that they had a proxy configuration that did not allow the connection to the WebSocket endpoint directly and did not support the WebSocket protocol.
The temporary solution was to disable using the proxy and everything started working. The long term solution is to edit the proxy's configuration (.pac file) to exclude the address of the WebSocket endpoint.
To disable the proxy, go to: Internet Explorer Options > Connections tab > LAN settings button > un-check Automatically detect settings.
Hope this helps someone.

In addition to making sure that the internet zone is not localhost (as in above answers), ensure that if https is used, then wss should be used.
This is not an issue in other browsers, but IE is abit more finicky.