# net::ERR_BLOCKED_BY_CLIENT

**Code:** `ERR_BLOCKED_BY_CLIENT` · **Category:** JavaScript · **Seen on:** JavaScript

A browser extension (ad blocker, privacy tool) blocked the request.

## Meaning

URLs containing words like ads, analytics, track, banner or affiliate are blocked by filter lists. Your own endpoints can be caught too.

## Common causes

- Ad blocker filter matching the URL
- Privacy extension blocking trackers/analytics
- Your API path contains “ads”/“analytics”

## Quick fix

1. Test in a private window without extensions
2. Rename endpoints that look like ad/tracking URLs
3. Don’t rely on third-party scripts for critical features

## Detailed fix by platform

### JavaScript

1. Serve analytics via first-party paths that don’t match common filter rules

## How to diagnose

1. **Extension** — Does it work with extensions disabled?
2. **URL** — Does it contain ad/track keywords?

---
Source: [WhatIsMyError](https://whatismyerror.com/errors/javascript/err-blocked-by-client)