Causes & Quick Fixes: "This Page Has Been Blocked by Strict Blocking Rules."

When you see a message like “This page has been blocked by strict blocking rules” (or related DevTools errors like net::ERR_BLOCKED_BY_CLIENT or ERR_BLOCKED_BY_RESPONSE), it can be confusing: Is your browser protecting you from harm, has the site blocked you intentionally, or is something else going wrong? This guide explains why it happens, helps you diagnose quickly, and provides step-by-step fixes.

Quick Summary

If you see “This page has been blocked by strict blocking rules” or DevTools errors like net::ERR_BLOCKED_BY_CLIENT / net::ERR_BLOCKED_BY_RESPONSE:

1. Open the page in Incognito — if it loads, an extension (uBlock/AdBlock) is probably blocking it.

2. If the page shows a Cloudflare block with a Ray ID, contact the site owner and give them the Ray ID.

3. If DevTools shows ERR_BLOCKED_BY_RESPONSE, check server response headers (CORS/CSP/WAF).

Use the sections below that match your role: Visitor, Developer / Site Owner, or Power User.

Understanding "This Page Has Been Blocked by Strict Blocking Rules"

This message is not a standard browser 404. It usually indicates that a security filter matched the page URL (from a browser extension like uBlock Origin, a site firewall/CDN such as Cloudflare, or server-side response rules). Strict blocking is an aggressive protection: instead of hiding ads or resources, it can stop the whole page from connecting to the server.

Common triggers: malware lists, tracking/redirect domains (shortened links), aggressive filter lists (e.g., Malware Domains, EasyPrivacy), overly strict WAF rules, or misconfigured CORS/CSP headers.

Diagnosis & Decision

Test	How to run it	Evidence / Interpretation	Immediate action
1. Incognito / Private window	Open URL in Incognito / Private	Page loads → client-side extension likely. Doesn't load → continue tests.	If it loads, go to Visitors — disable extension/whitelist.
2. Different network	Try mobile data / another Wi-Fi / disable VPN	Works on mobile but not on original network → network/ISP/corp firewall.	Use another network or contact network admin.
3. DevTools: Network tab	F12 → Network → Preserve log → reload	net::ERR_BLOCKED_BY_CLIENT → browser extension blocked. net::ERR_BLOCKED_BY_RESPONSE → server/WAF/CORS/CSP.	Save HAR and follow the corresponding dev or visitor steps.
4. Block page shows Ray ID	Look for Cloudflare/other CDN block page with Ray ID	Ray ID present → CDN/WAF / server-side firewall blocked request.	Contact site owner/support with Ray ID (see template).
5. cURL header check	curl -I -L 'https://example.com/path'	Missing/incorrect CORS/CSP/X-Frame headers or unexpected redirects → server misconfiguration or blocked response.	Fix headers or redirect logic (see Dev section).
6. Nothing obvious	After above, still unclear	Possible false positive, rare filter lists, or complex proxy config.	Collect HAR, screenshots, timestamp and escalate to site admin or filter list maintainer.

Use the row that matches your evidence. For example:

Incognito loads + DevTools shows ERR_BLOCKED_BY_CLIENT → follow Visitors: disable/whitelist extensions;

Cloudflare block with Ray ID → follow Developers: look up Ray ID in Cloudflare; 

ERR_BLOCKED_BY_RESPONSE → follow Developers: check CORS/CSP and server headers.

For Visitors: Quick Fixes (Easy → Medium)

These are for everyday users—focus on low-risk, quick actions.

1. Incognito / Private window

Open the URL in an incognito/private window. If it loads, a browser extension is blocking the page.

2. Disable ad/privacy extensions temporarily

Chrome: Menu → More tools → Extensions → toggle off uBlock/AdBlock/DuckDuckGo.

If it loads, re-enable extensions and whitelist the site instead of leaving protection off.

Tip: Disable one extension at a time to identify the responsible one.

3. Use uBlock’s “Proceed” / temporary bypass

Some strict-block pages offer a short “Proceed” (≈120s). Use this only for sites you trust. Prefer temporary proceed over permanent global changes.

4. Try a different network or clear cache

Switch to mobile data or another Wi-Fi. Disable VPN. Clear cache & cookies: Chrome Settings → Privacy → Clear browsing data.

For advanced users, a proxy can act as a temporary alternate network, helping confirm whether the block is tied to IP reputation or location. (Tip: Always use proxies responsibly and in compliance with the website’s terms.)

5. If you see a Cloudflare block (Ray ID shown)

Copy the Ray ID and timestamp, then contact the website owner (support email, Twitter, or alternate contact). Include the Ray ID and time — this allows the site owner to find the exact firewall event.

Support template:

Hello,

 

I was blocked while visiting a page on your site.

 

URL: https://example.com/page

Time (UTC): 2026-01-15 07:34:22

Ray ID: 1234567890abcdef

My IP: 203.0.113.45

Browser: Chrome 109.0.5414.87

 

Please check your Cloudflare firewall events for that Ray ID and let me know what I should try next. I can attach a HAR file or screenshot if helpful.

 

Thanks,

[Name]

For Developers & Site Owners: Systematic Check

If visitors report this issue, follow these steps to reproduce, diagnose, and fix.

1. Reproduce & collect diagnostics

Ask the visitor to provide:

• Full URL
• Screenshot with Ray ID (if present)
• Browser & version
• Timestamp (UTC)
• HAR file (see below)

Try loading the page yourself from multiple networks (home, mobile data) and in incognito. To reliably reproduce user reports, test the page from multiple IP locations, many teams use ISP proxies to simulate different regions, ISPs, and IP reputations without relying on random VPN endpoints.

2. Check CDN/WAF logs (Cloudflare example)

Cloudflare Dashboard → Security → Events or Firewall → filter by Ray ID or timestamp.

Identify which rule fired (Bot Fight Mode, OWASP rule, Rate Limit, IP Reputation).

Remediation options:

• Change Action: Block → Challenge (Captcha) for borderline traffic.
• Narrow the rule conditions (match specific URI patterns instead of broad host or UA patterns).
• Add an Allow rule for verified IP ranges or partners.
• Avoid disabling protections globally.

3. Inspect server response headers (CORS/CSP/X-Frame)

If DevTools shows ERR_BLOCKED_BY_RESPONSE, the server response or security headers are likely the cause.

Useful commands

# show response headers

curl -I -L 'https://example.com/path'

 

# verbose to see redirects and TLS details

curl -v 'https://example.com/path' 2>&1 | sed -n '1,120p'

Common headers to check / set

Access-Control-Allow-Origin: https://example.com

Content-Security-Policy: default-src 'self' https:;

X-Frame-Options: SAMEORIGIN

Example Nginx lines

add_header 'Access-Control-Allow-Origin' 'https://example.com';

add_header 'Access-Control-Allow-Methods' 'GET, POST, OPTIONS';

add_header 'Content-Security-Policy' "default-src 'self' https:; script-src 'self' https://cdn.example.com;";

4. Third-party scripts & graceful degradation

Don’t make critical UX depend synchronously on third-party scripts (analytics, ads, widgets). Load them asynchronously, and render fallback UI if blocked. Example strategies:

• Lazy-load third-party scripts after core content.
• Use rel="preload" or async/defer.
• Wrap calls in timeouts and fallback handlers.

For automated monitoring or integrations, rotating proxies are widely used to avoid shared-IP rate limits while respecting crawl and access policies.

5. Improve the block-page & support UX

If you control the block page, display Ray ID and timestamp prominently and provide an alternate contact method not blocked by the same rule (e.g., a public email or a form on a different subdomain). This reduces friction for blocked visitors and helps support teams quickly locate firewall events.

Power Users / Site Admins: uBlock Origin Controls (Advanced)

What strict blocking does

Strict blocking prevents the root document from loading for domain-only filters (e.g., ||example.com^). It’s more aggressive than blocking only third-party resources.

Safe bypass options

Temporary proceed on the block page (~120s).

Per-site allow: while on the site, click uBlock icon → press the power button → reload.

Per-site rule (preferred over global disables):

no-strict-blocking: example.com true

Add via: uBlock Dashboard → My rules → Paste rule → Save → Commit.

Filter list management

If false positives are frequent, uncheck specific aggressive lists (e.g., Malware Domains, Hosts file, EasyPrivacy) instead of disabling all protection.

FAQs

Q: Is it safe to click “Proceed” on a strict-block page?

A: Only for sites you trust. The proceed option is usually temporary and safer than globally disabling your blocker.

Q: What does net::ERR_BLOCKED_BY_CLIENT mean?

A: That error indicates the client (your browser or an extension) blocked the request — commonly a privacy/AdBlock extension.

Q: What does net::ERR_BLOCKED_BY_RESPONSE mean?

A: The server or a proxy returned a response that the browser considered blocked — often due to CORS/CSP mistakes or WAF actions.

Q: How can site owners reduce false positives?

A: Narrow WAF rules, prefer Challenge rather than Block for edge cases, publish clear support instructions and include Ray IDs on block pages.

Final Thoughts

These blocks protect you, so bypass judiciously. If stuck, check r/uBlockOrigin or SuperUser. For site owners, user-friendly fixes boost SEO by reducing bounce rates—happy users mean better rankings. Apply these steps, and you'll browse freely again.