How to fix Vercel Security Error Code 99 "Failed to verify your browser" while using VPN connection?

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# How to fix Vercel Security Error Code 99 "Failed to verify your browser" while using VPN connection?

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Questor 3467 (@questor-3467) · 2026-08-06 · ♥ 1

This is a tech support question about Vercel blocking my Browser from access a client website protected by Vercel software.

The website I am trying to access recently switched to Vercel Security Checkpoint software without notice to registered users like me.  Vercel  now blocks my access to their 3rd Party [www.Bidfta.com](https://www.bidfta.com) website whenever I use Malwarebytes VPN software with a USA access point for a secure connection.

When I now access the [www.bidfta.com](https://www.bidfta.com) website with VPN, I get a Vercel Error Code 99 that says "Failed to verify your browser".   A second line appears that says "Vercel Security Checkpoint iad1::1786066067-xgbMAd3njSvmytaXaxvZKv4GrRYhwMsw"

I cannot tell what is the Vercel website IP address I should use to enable a Malwarebytes VPN IP address exception for Vercel access using dual-tunneling. I experience this same VPN connect problem when I use a "clean" Firefox Browser (no extensions active) and USA VPN connection.

When I disable VPN, I can connect to [Bidfta.com](https://bidfta.com) and Vercel with no problem and everything seems to work correctly.   My VPN access was not blocked on the [Bidfta.com](https://bidfta.com) website until Vercel Security Checkpoint was recently implemented.

Regarding the error message, I called the website's customer support department for help and they do not know what to do nor whom I should contact regarding this concern.

I have a fairly standard setup as a client end-user on a Win11 Pro Laptop, I use the latest version of Javascript 64-bit. The Browser I prefer to use is the latest version of Mozilla Firefox Win11 64-bit.  My Win11 Pro Laptop also uses the all of the latest Microsoft updates and has Malwarebytes VPN installed.

How can I fix my end-user Win11 Laptop connection with VPN to the [Bidfta.com](https://bidfta.com) website so I can correctly use VPN access without getting this Error Code 99  "Failed to verify your browser" error?

After additional searching on the Internet, I found the following GitHub summary., but I am unsure if I can do anything on the client side since the problem and coding is with the Vercel Web Application Firewall (WAF)...

# Browser Navigation Gets Stuck at Vercel Security Checkpoint

[https://github.com/activepieces/activepieces/issues/10639](https://github.com/activepieces/activepieces/issues/10639)

"A "Vercel Security Checkpoint" error code (such as Code 11, Code 99, or Code 705) means ****Vercel's Web Application Firewall (WAF) has flagged your browser session or IP address as a potential bot****. This blocks the page and prompts a "Failed to verify your browser" challenge. \[1, 2, 3, 4, 5\]

**Common Causes & Fixes**

* **VPN or Proxy Usage:** Privacy VPNs often share IP ranges heavily flagged by automated DDoS mitigations. Disabling your VPN usually resolves Code 99 or Code 705 errors. \[1\]
* **Strict Privacy Browsers / VMs:** Browsers like LibreWolf, Tor, or running inside a virtual machine (VM) can strip or alter hardware and WebGL signals. Re-enabling graphics acceleration, turning on WebGL, or switching to a standard host browser fixes Code 11. \[1, 2\]
* **Browser Extensions:** Aggressive ad-blockers or script-blockers can interfere with Vercel's background fingerprinting challenges. Try disabling them temporarily or opening an unmodded incognito window. \[1, 2\]
* **False Positives:** Sometimes Vercel’s automated rules misidentify legitimate mobile or desktop traffic. If you manage the site, you can review or adjust settings under the **Vercel Project Security Settings**. \[1, 2, 3, 4\]

**How to Fix It as a Visitor**

* **Disable VPN/Proxies:** Turn off any active virtual private networks, custom DNS configurations, or strict privacy relays that alter your IP reputation. \[1, 2\]
* **Clear Browser Data:** Delete cookies and site data for the specific domain, then reload the page. \[1\]
* **Check Extensions:** Turn off ad blockers, script blockers, or privacy extensions (like uBlock Origin or Privacy Badger) that might block Vercel's challenge script. \[1, 2\]
* **Switch Browsers/Settings:** Try opening the site in a clean profile or standard browser, ensuring JavaScript and JIT (Just-In-Time) compilation are enabled. \[1, 2, 3\]

**How to Fix It as a Site Owner**

* **Disable Attack Mode:** Log into your Vercel Dashboard, go to your project settings, navigate to the **Security** section, and toggle off **Attack Challenge Mode** if it was falsely triggered. \[1\]
* **Review Firewall Rules:** Check your edge firewall configurations for overly aggressive bot rules or misconfigured block lists. \[1\]
* **Contact Support:** If the block persists falsely, reach out to **Vercel Support** to request a manual block override or investigation into edge mitigation logs. \[1, 2\]