ERR_BLOCKED_BY_CLIENT from AdBlock plugin

Product Support

AI-generated summary

A user Pugwash reported an “ERR_BLOCKED_BY_CLIENT” error when editing a post in Chrome, specifically on a topic containing the word “advertising.” The error appeared only in Chrome (v45.0.2454.101 m) on Windows 8/10, not in IE11 or on macOS Chrome. After investigation, Pugwash confirmed the issue was caused by the AdBlock plugin (v2.41.2), which blocks XHR requests containing “advertising” in the URL — even on Discourse’s friendly URLs like /t/advertising-test/329. codinghorror suggested checking for browser plugins or proxies, which led to the solution. Though not a Discourse bug, the issue is worth noting for others encountering similar behavior. techAPJ was unable to reproduce the issue on macOS Chrome, confirming the problem is environment-specific. The fix is to disable AdBlock or adjust its filters when editing posts with advertising-related terms.

1

Here’s the post in question

Whenever I attempt to edit the subject or the body, I get a modal error message:

Sorry, an error has occurred.

When I inspect the network activity in Chrome (Version 45.0.2454.101 m) I see the following:

The error is isolated only to this page, all other pages work fine. I believe @zogstrip and @techAPJ have admin access our Discourse instance, if you want to reproduce.

Thanks!

EDIT:

Tested in IE 11 and it works fine, just not in Chrome.

2

Hmm @techapj can you try to repro?

3

I can’t repro it on my MacBook Pro (OS X Yosemite) Chrome Version 45.0.2454.101 (64-bit).

4

Thanks for taking a look!

Here’s what I’m seeing:

client-blocked- error.gif639×171 141 KB

  • I’m using Windows 8, Chrome 45.0.2454.101 m
  • Also had the same issue on my home machine which is Windows 10 (Chrome.. not sure which version?).
5

Are you sure there is not anti virus or upstream proxies interfering with the request? Are you using any Chrome plugins, have you tried in Chrome safe mode with all plugins disabled?

Blocked by client usually means something in your box (or browser) is interfering.

6

You’re absolutely right. I disabled AdBlock (2.41.2) and it worked!

I’m not 100% sure how AdBlock works, although given that the topic of this post is about Advertising that would make sense.

Thanks!

EDIT:

I replicated this in try.discourse by creating a post with the word “advertising” in the subject. Initial post creation is fine but future saves initiate a post back to the friendly URL Discourse creates (http://try.discourse.org/t/advertising-test/329). I think AdBlock simply works on the basis of inspecting and blocking HTTP calls, so there’s a rule there that will block XHR calls if the word “advertising” is found in the URL.

Not really a Discourse issue but it may be useful for anyone else encountering the same behaviour.