[ajax] Getting "net::ERR_BLOCKED_BY_CLIENT" error on some AJAX calls

Recently I've realised that, some adblocker extensions (such as adBlocker plus) block some Ajax calls. I get that error on the console:

GET http://localhost/prj/conn.php?q=users/list/ net::ERR_BLOCKED_BY_CLIENT 

Why does it block some Ajax call but not the others and what causes that? Is there any workaround other than telling user to turn off adblocker?

This question is related to ajax google-chrome-extension firefox-addon

The answer is


Opera Blocker and others check all files/urls in Network. Then compares to the list. It is EasyPrivacy and EasyList. If your file/url in this, your will be ban. Good luck.

So... I find FilterLists for all addBlockers!


I've discovered that if the filename has 300 in it, AdBlock blocks the page and throws a ERR_BLOCKED_BY_CLIENT error.


In my case it was a Chrome extension and Firefox add-on by Avira called "Avira Browser Safety". I had problems with version 1.7.4. In my specific case I wanted to login to a website called gliffy.com for making diagrams, but after logging in I got an blank page. If you use F12 (console) in Chrome you can see all these ERR_BLOCKED_BY_CLIENT (and other) errors.


Add PrivacyBadger to the list of potential causes


As it has been explained here, beside of multiple extensions that perform ad or script blocking you may aware that this may happen by file names as below:

Particularly in the AdBlock Plus the character string "-300x600" is causing the Failed to Load Resource ERR_BLOCKED_BY_CLIENT problem.

As shown in the picture, some of the images were blocked because of the '-300x600' pattern in their name, that particular text pattern matches an expression list pattern in the AdBlock Plus.

ERR_BLOCKED_BY_CLIENT problem


If your URL contains words such as "advert", "ad", "doubleclick", "click", or something similar…

For example:

  • GET googleads.g.doubleclick.net/pagead/id
  • static.doubleclick.net/instream/ad_status.js

…Then ad-blocker will block it.


I find a case is if your url contains the key word banner, it will blocked too.


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