← Glossary / Redirect Loop Error

What is Redirect Loop Error?

Redirect Loop Error occurs when a server responds to an HTTP request with a 3xx status code pointing to a new URL, which then redirects back to the original URL or forms an infinite cycle. For scraping pipelines, this isn't just a failed request—it's a silent resource sink that exhausts connection pools, inflates proxy bandwidth costs, and halts data extraction until the crawler hits its maximum redirect threshold and throws an exception.

HTTP 3xxState ManagementProxy BandwidthCookie RejectionScraping Errors
// 02 — definitions

Trapped in
the cycle.

Why servers bounce your crawler between endpoints indefinitely, and how to break the loop before it drains your proxy budget.

Ask a DataFlirt engineer →

TL;DR

A redirect loop happens when URL A points to URL B, and URL B points back to URL A. In scraping, this is rarely a site misconfiguration; it's usually an anti-bot mechanism or a state failure—like a target demanding a session cookie your client failed to store, causing an infinite bounce between the login wall and the target page.

01Definition & structure
A redirect loop occurs when an HTTP client receives a 3xx status code (like 301 Moved Permanently or 302 Found) with a Location header, follows it, and eventually receives another redirect pointing back to a URL it has already visited in the same chain. Because automated clients are programmed to follow redirects, this creates an infinite cycle that only ends when the client's internal safety limit (max redirects) is triggered.
02The cookie rejection loop
The most common cause of redirect loops in scraping is state failure. A target server receives a request without a session cookie. It responds with a 302 redirect to an initialization endpoint, attaching a Set-Cookie header. If the scraper does not store this cookie and attach it to the next request, the initialization endpoint sees another stateless request and redirects back to the start. The loop continues until the connection is killed.
03Geo-blocking and localization loops
When using proxy networks, your exit IP's geolocation might conflict with the requested URL. If a scraper requests /en-gb/product using a US residential proxy, the server might issue a 302 redirect to /en-us/product based on the IP. If the scraper's logic forces it to re-request the GB version, or if the US endpoint has a conflicting canonical rule, the crawler gets trapped bouncing between regional subdirectories.
04How DataFlirt handles it
We treat redirects as state transitions, not just network hops. Our fetch layer maintains a strict cookie jar and header coherence across all 3xx responses. We cap linear redirects at 5 hops to prevent proxy bandwidth drain, and we run a real-time cycle detection algorithm: if a URL appears twice in the same request chain, the worker immediately drops the connection, flags the URL, and moves to the next item in the queue.
05The hidden cost of loops
Redirect loops are expensive. If your scraper uses a default HTTP client that allows 30 redirects, a single looping URL will consume 30 HTTP requests worth of proxy bandwidth and connection time before failing. At scale, a poorly configured scraper hitting a tarpit can burn gigabytes of premium residential proxy data without extracting a single record.
// 03 — the mechanics

Detecting and
capping loops.

Standard HTTP clients like requests or Axios default to 30 or 50 redirects before throwing an error. In a scraping context, that default is dangerously high. DataFlirt uses tight thresholds and cycle detection to kill loops early.

Cycle detection hash = H(chain) = MD5(Σ URLi)  →  abort if URLnew ∈ chain
If a URL appears twice in the same request chain, kill the connection immediately. DataFlirt fetch layer
Bandwidth cost of a loop = C = Nredirects × (Header_Size + Proxy_Overhead)
A 30-hop loop wastes proxy bandwidth without returning a single byte of payload. Infrastructure economics
Safe redirect threshold = Rmax = 5
Legitimate web routing rarely exceeds 3 hops. Anything over 5 is almost certainly a state failure. DataFlirt pipeline SLO
// 04 — network trace

The cookie rejection
bounce.

A live trace of a stateless scraper attempting to access a protected catalog. The server issues a Set-Cookie on the 302, but the scraper drops it, causing an infinite loop.

HTTP/2302 FoundState failure
edge.dataflirt.io — live
CAPTURED
// Hop 1: Initial request
GET /catalog/industrial-valves
Host: target-mfg.com
Response: 302 Found
Location: /challenge/verify?next=/catalog/industrial-valves
Set-Cookie: session_id=temp_8819; Path=/

// Hop 2: Scraper follows redirect (but drops cookie)
GET /challenge/verify?next=/catalog/industrial-valves
Cookie: <empty> // State lost
Response: 302 Found
Location: /catalog/industrial-valves

// Hop 3: Back to start
GET /catalog/industrial-valves
Cookie: <empty>
Response: 302 Found
Location: /challenge/verify?next=/catalog/industrial-valves

// Pipeline intervention
sys.router: CYCLE DETECTED (A -> B -> A)
action: Connection terminated at hop 3
error: RedirectLoopError: State coherence failure
// 05 — root causes

Why the server
keeps bouncing you.

Redirect loops in scraping are rarely accidental. They are usually the result of your client failing to maintain the state the server expects. Ranked by frequency across our monitoring fleet.

PIPELINES MONITORED ·   300+ active
AVG HOPS TO KILL ·  ·  ·  3.2 hops
UPDATED ·  ·  ·  ·  ·  ·  2026-05-19
01

Cookie rejection

state failure · Client fails to store and return Set-Cookie headers across hops
02

Geo-location mismatch

proxy routing · US proxy hits UK site, redirects to /en-us/, which redirects back
03

Protocol downgrade

network layer · Infinite bounce between HTTP and HTTPS endpoints
04

User-Agent routing

header anomaly · Mobile UA string triggers redirect to m.site, which rejects the IP
05

Trailing slash rules

site config · Strict normalization rules conflicting with load balancers
// 06 — our architecture

Break the chain,

before it breaks your concurrency budget.

Infinite redirects are a state management problem masquerading as a network error. When a scraper drops a Set-Cookie header or presents a mismatched User-Agent, the target server tries to correct the state by redirecting to an initialization endpoint. If the scraper remains stateless, the cycle repeats. DataFlirt's fetch layer maintains strict state coherence across redirect chains, ensuring cookies, referers, and TLS fingerprints survive the hop. If a cycle is detected, we kill the connection instantly—saving proxy bandwidth and freeing the worker for the next URL.

Redirect chain analysis

Live trace of a quarantined URL in a DataFlirt pipeline.

request.url /api/v1/inventory
redirect.count 3 hops
chain.cycle detectedA -> B -> A
failure.reason cookie_rejection
action.taken quarantine_url
bandwidth.saved ~42 KB
worker.status released

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// 07 — FAQ

Common
questions.

Common questions about handling 3xx responses, managing state across hops, and preventing proxy bandwidth waste.

Ask us directly →
What is the difference between a redirect loop and max redirects exceeded? +
A redirect loop is a cycle: A redirects to B, and B redirects back to A. "Max redirects exceeded" is a linear chain that is too long: A to B to C to D, eventually hitting the client's hard limit (e.g., 30 hops). Both result in failure, but a loop can be detected and killed much earlier by hashing the URL chain.
Why does the page load fine in my browser, but my scraper gets a redirect loop? +
Your browser automatically manages state. When the server issues a 302 with a Set-Cookie header, the browser stores it and sends it on the next request. If your scraper is using a basic HTTP client without a configured cookie jar, it drops the cookie. The server sees a fresh, unauthenticated request and redirects you again.
How do I fix a cookie-based redirect loop? +
You must persist state across the redirect chain. In Python's requests, use a Session() object instead of bare requests.get(). In Node.js, use a library with built-in cookie jar support. Ensure that cookies set during intermediate 3xx responses are attached to the subsequent GET request.
Do anti-bot systems use redirect loops intentionally? +
Yes. It's a form of tarpitting. Instead of issuing a hard 403 Forbidden, some WAFs will trap suspected bots in an infinite redirect loop. This forces poorly written scrapers to waste their own CPU cycles and proxy bandwidth, effectively neutralizing the threat without revealing the exact detection mechanism.
How does DataFlirt prevent proxy bandwidth waste from loops? +
We don't wait to hit a max-redirect limit. Our fetch layer hashes every URL in the redirect chain in real time. If a URL appears twice, we immediately terminate the TCP connection. We also cap linear redirects at 5 hops, which is well below the default of most HTTP libraries, ensuring rogue chains don't burn residential proxy data.
Should I just disable redirect following in my scraper? +
No. Many legitimate sites use 301s for canonical URL enforcement or 302s for load balancing and localization. If you disable redirect following entirely, you will fail to extract data from perfectly valid targets. The correct approach is to follow redirects, but strictly manage state and enforce tight cycle-detection limits.
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// 08 — keep reading

Related glossary terms

Scraping Errors

ERR_TOO_MANY_REDIRECTS

The browser-level exception thrown when a redirect chain exceeds safe limits.

Read →
Scraping Errors

Max Redirects Exceeded

When a linear redirect chain is too long, indicating a routing failure.

Read →
Web Scraping

Redirect Following

The mechanics of automatically traversing 3xx responses while maintaining client state.

Read →
Anti-Scraping

Cookie Validation Failure

The root cause of most redirect loops: failing to return the expected session token.

Read →