# Klaviyo: Major incident: Cloudflare incident disrupting onsite events

**Summary:** Klaviyo reported a major Cloudflare-related outage: onsite forms appeared, but requests, events and subscriptions did not process; preference pages errored and API calls returned 403s. It started 2025-11-18 13:58 UTC and resolved 2025-11-18 19:06 UTC, lasting 5 h 7 min. Fixes were implemented, and all affected components were operational at resolution. _(machine-written, sol)_
- Kind: Major incident · Label: outage (model (Jev))
- Changed: 2025-11-18 13:58 UTC · Detected: 2026-10-17 18:22 UTC
- [Source: https://stspg.io/k0fc5ckvcp0f](https://stspg.io/k0fc5ckvcp0f)
- [Company: Klaviyo](https://rewindex.com/company/klaviyo.md)
- Versions: before (none: first archived) → after incident\_version:249/1ht269mmldck@6d024a6ac98f
- Change 1 of 1 for this incident

## What changed

**1. Added: Title**

```diff
+ Cloudflare incident disrupting onsite events
```

**2. Added: Impact**

```diff
+ major
```

**3. Added: Status**

```diff
+ resolved
```

**4. Added: Start time**

```diff
+ 2025-11-18 13:58 UTC
```

**5. Added: Resolved time**

```diff
+ 2025-11-18 19:06 UTC
```

**6. Added: Affected components**

```diff
+ Consent Pages, Klaviyo API, Lists, List Subscription, Server-side, Sign-up Forms, Signup Forms, Unsubscribe & Preference Pages
```

**7. Added: Update** (identified) · 2025-11-18 13:58 UTC

```diff
+ Cloudflare declared an incident around 6:30 am US Eastern causing all onsite activities, such as unsubscribe and subscribe preference pages and onsite form submissions to error out. Forms appear, but no requests or related events or subscriptions are processing. API calls are also experiencing 403s. https://www.cloudflarestatus.com/incidents/8gmgl950y3h7 We're currently investigating mitigation steps for the affected features.
```

**8. Added: Update** (monitoring) · 2025-11-18 14:34 UTC

```diff
+ Fixes have been implemented for some services and we are monitoring the issues.
```

**9. Added: Update** (resolved) · 2025-11-18 19:06 UTC

```diff
+ This incident has been resolved, as of 2 pm US eastern. All affected components are operational.
```

## History of this incident

| When (UTC) | Change | Label |
| --- | --- | --- |
| 2025-11-18 13:58 UTC | Major incident: Cloudflare incident disrupting onsite events (this change) | outage |

All Klaviyo changes: [timeline](https://rewindex.com/company/klaviyo/changes.md)
_Diff excerpts are shown on normalized text: dates, counters and tokens appear as ‹date›, ‹count›, ‹tok›; noise-only edits are hidden. Rewindex shows the changed passages, not a copy of the page._


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Canonical: https://rewindex.com/change/idf7424142696f8 · Markdown: https://rewindex.com/change/idf7424142696f8.md · JSON: https://rewindex.com/api/v1/changes/idf7424142696f8 · Generated 2026-10-18T01:54:27.776Z