← Glossary / Imperva Block Page

What is Imperva Block Page?

Imperva Block Page is the interstitial HTML response served by Imperva's Advanced Bot Protection when a client fails its JavaScript challenge or exhibits anomalous request patterns. For a scraping pipeline, hitting this page means your session identity is burned, your IP is likely flagged, and the target data is inaccessible until you rotate your fingerprint and network exit node.

Anti-ScrapingWAFBot ProtectionJavaScript ChallengeIncapsula
// 02 — definitions

The end of
the line.

What happens when Imperva decides your request looks more like a Python script than a human using Chrome.

Ask a DataFlirt engineer →

TL;DR

The Imperva Block Page (often containing the infamous "Incapsula incident ID") is a hard stop for automated traffic. It triggers when your TLS fingerprint, IP reputation, or JavaScript execution environment fails to match the expected profile of a legitimate browser. Bypassing it requires a complete overhaul of your client's identity stack.

01Definition & structure
The Imperva Block Page is an HTML response returned by Imperva's Web Application Firewall (WAF) and Advanced Bot Protection (ABP) systems. It is served when a request is deemed malicious or automated. The page typically features a "Pardon Our Interruption" message and an Incapsula incident ID, which administrators use for debugging. Receiving this page means your request never reached the origin server.
02How it works in practice
When a client makes a request to an Imperva-protected domain, the edge node evaluates the request's TLS fingerprint, HTTP headers, and IP reputation. If the request is suspicious but not definitively malicious, Imperva serves a JavaScript challenge. If the client fails to execute the JS, generates an invalid telemetry payload, or exhibits blatant bot behavior (like a mismatched JA3 hash), the edge node terminates the flow and serves the block page with a 403 Forbidden status.
03The role of the Reese84 cookie
The core of Imperva's bot protection revolves around the reese84 cookie. This cookie is generated after the client successfully executes Imperva's heavily obfuscated JavaScript challenge, which collects hardware, browser, and behavioral telemetry. If your scraper attempts to access an endpoint without a valid, unexpired reese84 cookie, it will almost certainly be routed to the block page.
04How DataFlirt handles it
We treat Imperva block pages as a failure of session identity, not just a network error. Our infrastructure proactively solves Imperva challenges using real browser engines bound to high-reputation residential IPs. We acquire the necessary clearance cookies and attach them to lightweight HTTP workers for the actual data extraction. If a session is flagged and receives a block page, we immediately burn the session, rotate the IP, and spin up a fresh browser context to re-acquire clearance.
05Did you know?
The name "Incapsula" still appears frequently in Imperva block pages and HTTP headers (like x-cdn: Incapsula). This is because Imperva acquired Incapsula in 2014 and integrated its cloud-based WAF and DDoS protection into the core Imperva product line. The legacy naming conventions remain deeply embedded in the network infrastructure.
// 03 — the block logic

How Imperva
scores your request.

Imperva evaluates a blend of network-layer signals and client-side telemetry. DataFlirt monitors these thresholds to ensure our fleet stays well below the block criteria.

Bot Risk Score = R = (w1·TLS_anomaly) + (w2·JS_failure) + (w3·IP_rep)
If R > threshold, the block page is served. Imperva ABP Architecture
Challenge Failure Rate = F = failed_challenges / total_challenges
High failure rates lead to subnet-level blocks. DataFlirt Pipeline Analytics
DataFlirt Evasion Rate = 1 - (block_pages_received / total_requests)
Maintained at > 0.998 across Imperva-protected targets. Internal SLO
// 04 — the block response

What an Imperva
block looks like.

A raw HTTP trace of a naive scraper hitting an Imperva-protected endpoint and receiving the block page instead of the target JSON.

HTTP 403IncapsulaHTML payload
edge.dataflirt.io — live
CAPTURED
// outbound request
GET /api/v1/inventory HTTP/2
user-agent: "python-requests/2.31.0" // fatal mistake

// inbound response
status: 403 Forbidden
server: "incapsula"
x-cdn: "Imperva"
set-cookie: "visid_incap_...; path=/; HttpOnly"
set-cookie: "incap_ses_...; path=/; HttpOnly"

// response body (truncated)
content-type: "text/html"
<html><head><title>Pardon Our Interruption</title>...
...Request unsuccessful. Incapsula incident ID: 123456789...

// pipeline outcome
extraction: failed
action: session burned, IP rotated
// 05 — block triggers

Why Imperva
blocks you.

The most common reasons a request is routed to the Imperva block page instead of the origin server, ranked by frequency across our monitoring fleet.

SAMPLE SIZE ·  ·  ·  ·    1.2M blocks
WINDOW ·  ·  ·  ·  ·  ·   30d trailing
UPDATED ·  ·  ·  ·  ·  ·  2026-05-19
01

Missing or invalid Reese84 cookie

JS challenge failure · Crucial for Advanced Bot Protection
02

TLS fingerprint mismatch

Network layer · JA3/JA4 doesn't match User-Agent
03

Datacenter IP detection

IP reputation · ASN belongs to AWS/GCP/DO
04

Headless browser leaks

Execution environment · navigator.webdriver = true
05

Rate limit exceeded

Behavioral · Too many requests per session
// 06 — evasion architecture

Solve the challenge,

don't just rotate the IP.

When you hit an Imperva block page, simply rotating your proxy isn't enough. Imperva's Advanced Bot Protection relies heavily on client-side telemetry gathered via obfuscated JavaScript. To consistently bypass the block, you must execute the challenge script in a pristine browser environment, generate a valid telemetry payload, and submit it to acquire the necessary clearance cookies. DataFlirt's infrastructure handles this lifecycle automatically, ensuring your extraction jobs never see the block page.

Imperva Clearance Flow

Trace of a successful session acquisition against an Imperva-protected target.

session.init residential_US
tls.fingerprint chrome_124
initial_request 200 OK (Challenge HTML)
js.execution telemetry generated
cookie.reese84 acquired
target_request 200 OK (JSON)
pipeline.status extracting

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// 07 — FAQ

Common
questions.

Common questions about the Imperva block page, Incapsula incident IDs, and how to maintain access to protected targets.

Ask us directly →
What is the Incapsula incident ID? +
It's a unique reference number generated by Imperva when a request is blocked. Site administrators can use this ID to look up the exact reason for the block in their Imperva dashboard. For scrapers, it's just confirmation that you've been caught.
Can I bypass the block page using a standard HTTP client? +
Rarely. While simple IP blocks might be bypassed by rotating proxies, Imperva's Advanced Bot Protection requires executing complex JavaScript to solve challenges and acquire clearance cookies. Standard HTTP clients like requests or axios cannot execute this JS.
How does DataFlirt handle Imperva-protected sites? +
We use a combination of high-quality residential proxies, perfect TLS fingerprinting, and real browser engines to execute Imperva's challenge scripts. Once a session acquires the necessary clearance cookies, we multiplex extraction requests through that session until the cookies expire.
Why am I getting blocked even with a residential proxy? +
Because Imperva looks at more than just your IP. If your TLS fingerprint screams 'Python' while your User-Agent claims to be 'Chrome', or if your headless browser leaks automation flags, Imperva will serve the block page regardless of how clean your IP is.
Is it legal to bypass an Imperva block page? +
Bypassing a WAF to access publicly available data is generally considered lawful in jurisdictions like the US and EU, provided you aren't breaching authenticated areas, causing denial of service, or violating specific terms of service. Always consult legal counsel for your specific use case.
How long do Imperva clearance cookies last? +
It varies by target configuration, but typically between 15 minutes and a few hours. DataFlirt's session managers monitor cookie validity and proactively solve new challenges before the existing clearance expires, ensuring uninterrupted data extraction.
$ dataflirt scope --new-project --target=imperva-block-page READY

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to extract.
We do the rest.

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