How to Fix ERR_BLOCKED_BY_CLIENT in Chrome

You’re debugging a frontend project when Chrome’s DevTools Network tab lights up red. The error reads net::ERR_BLOCKED_BY_CLIENT. Your analytics script won’t load, a third-party font fails silently, or an API request never completes. The server isn’t rejecting your request—something on your own machine is blocking it.

This guide explains what causes the ERR_BLOCKED_BY_CLIENT Chrome error and walks through practical troubleshooting steps for developers diagnosing blocked network requests.

What ERR_BLOCKED_BY_CLIENT Actually Means

Unlike server-side errors (404, 500), this Chrome request blocked error originates locally. The “client” is your browser. Chrome is telling you: “I tried to fetch this resource, but something on this device stopped me.”

The request never reaches the server. Instead, an extension, browser policy, or local configuration intercepts and cancels it before departure.

This distinction matters. You won’t find answers in server logs or network infrastructure. The solution exists within your browser environment.

Common Causes Developers Encounter

Browser Extensions: The Primary Culprit

Extensions with network-filtering capabilities cause most ERR_BLOCKED_BY_CLIENT errors. These include:

• Ad blockers (uBlock Origin, AdGuard, AdBlock)
• Privacy tools (Privacy Badger, Ghostery)
• Security extensions (script blockers, anti-tracking tools)

These extensions maintain filter lists—rules that match URL patterns. When a request URL triggers a filter, the extension blocks it. A request to analytics.example.com/track.js might match a filter targeting tracking scripts, even if it’s essential for your application.

Manifest V3 and Extension Changes

Chrome’s shift to Manifest V3 has changed how extensions intercept requests. Extensions built on the older Manifest V2 architecture may behave differently or become disabled entirely as Chrome phases out support. If you recently updated Chrome and started seeing blocked requests, an outdated extension losing functionality—or a newly updated one changing its blocking behavior—could be responsible.

Enterprise and Managed Browser Policies

In corporate environments, IT administrators deploy Chrome policies that restrict network access. These policies can block specific domains, resource types, or URL patterns without any visible extension.

Check chrome://policy to see active policies. If you’re on a managed device, this is often an overlooked source of blocked-by-client-style errors—even when no extension is installed.

Filter List False Positives

Your resources might trigger blocks unintentionally. File paths containing strings like /ads/, /tracking/, or /banner/ commonly match filter rules. A legitimate image at /assets/ads-campaign/hero.png could get blocked purely because of its path.

How to Fix ERR_BLOCKED_BY_CLIENT

Step 1: Test in Incognito Mode

Open an Incognito window (Ctrl+Shift+N on Windows, Cmd+Shift+N on Mac). By default, extensions don’t run in Incognito unless explicitly enabled.

If the request succeeds in Incognito, an extension is blocking it. If it still fails, the cause is likely a browser policy or Chrome flag.

Step 2: Isolate the Blocking Extension

To disable extensions for Chrome troubleshooting:

1. Navigate to chrome://extensions
2. Toggle extensions off one by one
3. Reload your page after each change
4. When the request succeeds, you’ve found the culprit

Start with ad blockers and privacy tools—they’re the most common offenders.

Step 3: Inspect the Block in DevTools

Open DevTools (F12), go to the Network tab, and reload. Failed requests show the error in the Status column. Click the request to see details.

Some extensions (like uBlock Origin) add their own DevTools panels showing exactly which filter rule triggered the block. This helps you understand whether to whitelist the domain or rename your resource.

Step 4: Check Browser Policies

Visit chrome://policy to view any active restrictions. On managed devices, policies like URLBlocklist can silently block requests. If policies are the issue, contact your IT administrator.

Step 5: Test in a Clean Profile

Create a fresh Chrome profile with no extensions or customizations:

1. Click your profile icon in Chrome
2. Select “Add” to create a new profile
3. Test your application in this clean environment

This eliminates cached settings, corrupted data, and all extensions simultaneously.

Step 6: Review Your Resource Naming

If you control the blocked resource, check its URL path. Rename files or directories that contain common filter-list triggers (/ad/, /tracking/, /banner/, /sponsor/). This prevents false positives across your users’ browsers.

When the Error Persists

If none of these steps resolve the issue, consider:

• Resetting Chrome flags at chrome://flags (click “Reset all”)
• Clearing browser cache and cookies
• Checking if antivirus software includes web filtering features

Conclusion

The ERR_BLOCKED_BY_CLIENT error means your browser—not the server—is stopping a request. Extensions are usually responsible, but managed policies and filter-list false positives also cause problems. Systematic isolation using Incognito mode, extension toggling, and clean profiles will identify the source. For developers, understanding this error prevents hours of debugging in the wrong place.

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