Why are my Cloudflare Workers failing?

Updated 2026-10-17

Short answer: a Worker that throws, or runs out of CPU or memory, fails the request it was handling, and visitors see an error page. The fix depends on which: a code bug, or work that's too heavy for the limits.

How to check it yourself

  1. In the Cloudflare dashboard, open Workers, then your Worker, then Metrics, and look at errors over time.
  2. Open Logs (or run wrangler tail) to see the actual exceptions.
  3. Errors marked as exceeding CPU or memory mean the work needs splitting, caching or moving.
  4. Match the time errors started against your last deploy of that Worker.

Why it matters

A Worker sits in front of your site or API, so when it throws an error, the visitor gets an error page even if your server is fine. Workers often handle redirects, headers, forms or API calls, so a failing Worker can break one feature quietly while the rest of the site loads.

Common causes

  • A new deploy introduced a bug in the Worker code.
  • The Worker calls an API or service that's down, slow or has changed.
  • It hits a CPU time or memory limit on some requests.
  • A secret or environment variable it needs was removed or renamed.

What Preventionlabs shows

With a read-only Cloudflare token connected, every report shows errors thrown by your Workers over time: how many requests failed and why (uncaught exception, out of CPU or out of memory), and the slowest run times. Pages Functions aren't included in this data.

Price

First report free, no card needed. Then A$50 a month, up to 10 domains.

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