Workers cache purge call results in error when run in local dev mode

[Shotster]

What versions & operating system are you using?

Wangler v4.123.0 on Intel Mac running Sequoia 15.7.3

Please provide a link to a minimal reproduction

replicated from example in blog post https://blog.cloudflare.com/workers-cache/#a-cache-between-every-worker-entrypoint

Describe the Bug

Either of the following work when deployed to workers.dev but error out when run in dev mode locally.

import { cache, WorkerEntrypoint } from "cloudflare:workers";

export class CachedEntrypoint extends WorkerEntrypoint {

	async fetch( request ) {
		// works fine
	}

	async invalidate1( pathToPurge ) {
		const result = await this.ctx.cache.purge( {  // Fails with "Cannot read properties of undefined (reading 'purge')"
			pathPrefixes : [ pathToPurge ],
		} )
	}

	async invalidate( pathToPurge ) {
		const result = await cache.purge( {  // Fails with "cache.purge is not a function"
			pathPrefixes : [ pathToPurge ],
		} )
	}

}

Please provide any relevant error logs

"status":500,"message":"cache.purge is not a function"

"status":500,"message":"Cannot read properties of undefined (reading 'purge')"

[workers-devprod]

Note

This is an automated, advisory triage report generated by workers-devprod. It is not an official maintainer response — a maintainer will follow up.

🤖 Automated triage report

Issue Triage: #15183

Summary

The cache API from cloudflare:workers (both the module-level cache.purge() and this.ctx.cache.purge()) works when deployed to workers.dev but throws errors in local dev mode.

Classification

• Type: Bug
• Component: packages/miniflare (local dev simulation; may require a workerd change)
• Severity: Medium
• Has Reproduction: Yes (minimal code sample + blog post reference; reproduced by automated triage)
• Quality: Complete

Findings

• Created: 2026-08-13
• Author: Shotster
• Version: Wrangler v4.123.0 (Intel Mac, macOS Sequoia 15.7.3)
• Labels: none
• Comments: 2 (both automated posts from workers-devprod; no human/maintainer/reporter replies)

Analysis

• The reporter provides a clear, minimal code sample derived from the official Cloudflare blog post ("A cache between every Worker entrypoint") with exact error messages for both access patterns: cache.purge is not a function (module-level cache import) and Cannot read properties of undefined (reading 'purge') (this.ctx.cache).
• Both patterns succeed when deployed but fail locally, indicating a local-dev vs. production parity gap: the cache API from cloudflare:workers appears unimplemented or not wired up in the local simulation.
• The bug was independently reproduced by the automated triage bot via Miniflare, confirming both errors — so no further information is needed from the reporter to begin investigation.
• Report quality is high (current version, OS, reproduction reference, precise error strings all present). The issue is not caught by any Step 2 close criterion: it is a fresh (same-day), reproducible, well-documented bug that is on-topic for workers-sdk.
• The fix most likely belongs in Miniflare's local dev runtime (exposing the cloudflare:workers cache binding), but may require a bundled-workerd change. Confirming which layer owns the fix — and whether it warrants a transfer to cloudflare/workerd — is the key next step.

Recommendation

Status: KEEP OPEN

Reasoning: This is a well-documented, reproducible bug describing a genuine parity gap between local dev and production for the cloudflare:workers cache API. It has been reproduced via Miniflare and has sufficient detail to investigate; it does not match any closure criteria.

Action: Route to the Miniflare/local-dev owners to determine whether the cache API from cloudflare:workers should be exposed in local dev or requires a workerd fix. Confirm the reporter's compatibility_date/compatibility_flags, verify against the latest Wrangler/Miniflare, and decide whether the issue should be transferred to cloudflare/workerd.

Suggested Labels: none (cannot confirm exact repo label names from the pre-fetched data)

Suggested Comment

Thanks for the detailed report and reproduction — we've confirmed both errors reproduce in local dev via Miniflare, while the same code works once deployed. This looks like a parity gap where the cache API from cloudflare:workers isn't yet available in local dev mode.

To help us narrow down the fix, could you share the compatibility_date (and any compatibility_flags) from your Wrangler config? We'll investigate whether this needs to be wired up in Miniflare's local dev runtime or in the bundled workerd version. We'll keep this open and follow up.

Structured summary (JSON)

{
  "issueNumber": 15183,
  "title": "Workers cache purge call results in error when run in local dev mode",
  "githubUrl": "https://github.com/cloudflare/workers-sdk/issues/15183",
  "recommendation": "KEEP OPEN",
  "difficulty": "medium",
  "reasoning": "Well-documented, reproducible bug: the cloudflare:workers cache.purge API works in production but errors in local dev mode, indicating a local-dev/production parity gap that was confirmed via Miniflare.",
  "suggestedAction": "Route to Miniflare/local-dev owners to determine whether the cloudflare:workers cache API should be exposed in local dev or requires a workerd fix; confirm the reporter's compatibility_date and verify against the latest versions.",
  "hasSuggestedComment": true,
  "suggestedLabels": []
}

[workers-devprod]

• Reproduction: ✅ Successfully reproduced. Both reported errors reproduced via Miniflare: this.ctx.cache.purge gives "Cannot read properties of undefined (reading 'purge')" and cache.purge gives "cache.purge is not a function".