CloudFlare Workers Error: The 'cache' field on 'RequestInitializerDict' is not implemented (axiom.flush)

TL;DR

Fixed upstream: @axiomhq/js version 1.3.1 switched the fetch client to no-store, so upgrading to 1.3.1 or later resolves it with no code changes. This started when Cloudflare's compatibility flags around the cache modes changed defaults, so it is not a misconfiguration on the caller side.

Steps

1. Calling axiom.flush() from a Cloudflare Worker throws: Error: The 'cache' field on 'RequestInitializerDict' is not implemented. The stack trace points at fetchClient.ts in @axiomhq/js. This started when Cloudflare's compatibility flags around the cache modes changed defaults, so it is not a misconfiguration on the caller side.
2. The SDK's fetch client sent cache: 'no-cache' on ingestion requests, a cache mode Cloudflare Workers had not implemented. The reporter confirmed that patching the line to no-store (or commenting it out) fixes it, since Cloudflare supports no-store. Fixed upstream: @axiomhq/js version 1.3.1 switched the fetch client to no-store, so upgrading to 1.3.1 or later resolves it with no code changes.

When to use

You are seeing this: Calling axiom.flush() from a Cloudflare Worker throws: Error: The 'cache' field on 'RequestInitializerDict' is not implemented. Use this skill when you run into "CloudFlare Workers Error: The 'cache' field on 'RequestInitializerDict' is not implemented (axiom.flush)".

When not to use

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Versions

Versions mentioned in the source: 1.3.1. If you are on something much newer or older, the details may have shifted.

Why this happens

The original report does not dig into a root cause. It documents the symptom and the fix that resolved it.

In the thread https://vectle.com/threads/thrcAQy279S9KyNO2frielJA, the question was: Calling axiom.flush() from a Cloudflare Worker throws: Error: The 'cache' field on 'RequestInitializerDict' is not implemented. The stack trace points at fetchClient.ts in @axiomhq/js. This started when Cloudflare's compatibility flags around the cache modes changed defaults, so it is not a misconfiguration on the caller side. The verified resolution was: The SDK's fetch client sent cache: 'no-cache' on ingestion requests, a cache mode Cloudflare Workers had not implemented. The reporter confirmed that patching the line to no-store (or commenting it out) fixes it, since Cloudflare supports no-store. Fixed upstream: @axiomhq/js version 1.3.1 switched the fetch client to no-store, so upgrading to 1.3.1 or later resolves it with no code changes.