Seeing Error Code 15 or Error Code 16 – This request was blocked by the security rules can be frustrating, especially when the website loads fine for others. These errors are not caused by your PC being infected. Instead, they are triggered by website-side security systems that flag your request as suspicious.
This issue commonly appears when browsing on Windows 11, but it can happen on any platform or browser.
This guide explains why Error 15 or 16 happens, what it means, and exact steps to fix or bypass it safely.
What Do Error Code 15 and Error Code 16 Mean?
These errors are generated by web application firewalls (WAFs), most commonly powered by services like Cloudflare, Akamai, or Imperva.
What’s happening behind the scenes:
- Your request was blocked by automated security rules
- The site thinks your traffic looks risky or abnormal
- The block happens before the website loads
Typical error messages include:
- Access denied
- This request was blocked by the security rules
- You don’t have permission to access this site
Common Reasons for Error Code 15 or 16
These blocks are usually triggered by one or more of the following:
- VPN or proxy usage
- Suspicious IP address reputation
- Browser extensions modifying requests
- Corrupted cookies or cache
- Too many rapid requests (rate limiting)
- Geographic or country-based restrictions
- Corporate, school, or ISP filtering
The website—not your computer—is enforcing the block.
How to Fix Error Code 15 or Error Code 16
Follow the steps below in order. After each step, refresh the page and check if the error is resolved.
1. Refresh and Try a Private / Incognito Window
Sometimes the block is session-based.
- Open a new Incognito / Private window in your browser.
- Paste the website URL directly.
- Try loading the page.
If it works here, cached data or cookies are likely the cause.
2. Clear Browser Cookies and Cache for the Website
Corrupted or flagged cookies often trigger security rules.
- Open browser Settings → Privacy and security.
- Click Cookies and other site data.
- Choose See all site data.
- Search for the affected website.
- Remove all cookies and stored data for it.
- Restart the browser and retry.
This resets how the site identifies your session.
3. Disable VPN, Proxy, or Secure DNS (Very Common Fix)
Security systems frequently block VPN traffic.
- Disconnect any active VPN.
- Open Settings → Network & Internet → Proxy.
- Turn Use a proxy server Off.
- If using browser-based secure DNS:
- Temporarily disable it
- Reload the website.
If the site loads now, your VPN IP was blocked.
4. Disable Browser Extensions Temporarily
Extensions can modify headers, scripts, or cookies.
- Disable all browser extensions.
- Restart the browser.
- Visit the website again.
If it works:
- Re-enable extensions one by one
- Ad blockers, script blockers, and privacy tools are the usual triggers
5. Try a Different Browser or Device
This helps identify whether the block is browser-specific.
- Open the site in another browser (Edge, Chrome, Firefox).
- If possible, test on:
- A mobile device
- Another network
If it works elsewhere, the issue is local to your setup.
6. Restart Your Router (Change IP Address)
Many Error 15/16 blocks are IP-based.
- Turn off your router for 5–10 minutes.
- Turn it back on and reconnect.
- Try accessing the site again.
This often assigns you a new public IP address.
7. Check Date, Time, and Region Settings
Incorrect system time can break security validation.
- Open Settings → Time & language → Date & time.
- Enable:
- Set time automatically
- Set time zone automatically
- Click Sync now.
Security systems rely heavily on accurate timestamps.
8. Avoid Rapid Refreshing or Automated Actions
Repeated requests can trigger rate-limiting rules.
- Avoid refreshing the page repeatedly
- Do not use auto-refresh extensions
- Do not submit forms multiple times quickly
Wait a few minutes before retrying.
9. Check If the Website Is Blocking Your Country or ISP
Some websites block traffic by region.
- Try accessing the site from a different network
- Check if others in your country report the same issue
- Public Wi-Fi or mobile data can help test this
This is entirely controlled by the website.
10. Contact the Website Owner (Last Resort)
If nothing works, the block must be removed server-side.
- Look for a Contact Us or Support page.
- Send them:
- The error code (15 or 16)
- The exact message shown
- Your public IP (optional)
- Ask them to whitelist or review the block.
Many sites unblock legitimate users on request.
Is Error Code 15 or 16 Dangerous?
No.
These errors mean:
- Your request was denied
- The site is protecting itself
- Your device is not harmed
It’s a false positive in most cases.
Wrapping Up
Error Code 15 or Error Code 16 – “This request was blocked by the security rules” is almost always caused by VPNs, IP reputation, cookies, extensions, or aggressive security filtering on the website itself. By clearing site data, disabling VPNs, testing another browser or network, and resetting your IP, most users can resolve the issue quickly.
If the block persists, only the website owner can remove it—but rest assured, your system is safe.
