--- description: Known issues and bugs to be aware of when using Workers. title: Known issues image: https://developers.cloudflare.com/og-docs.png --- [Skip to content](#main-content) > Documentation Index > Fetch the complete documentation index at: https://developers.cloudflare.com/workers/llms.txt > Use this file to discover all available pages before exploring further. # Known issues Last updated Aug 25, 2026|Copy as Markdown|[View as Markdown](https://66f4ea29.previews.developers.cloudflare.com/workers/platform/known-issues/index.md)|[Agent setup](https://66f4ea29.previews.developers.cloudflare.com/agent-setup/) Below are some known bugs and issues to be aware of when using Cloudflare Workers. ## Route specificity * When defining route specificity, a trailing `/*` in your pattern may not act as expected. Consider two different Workers, each deployed to the same zone. Worker A is assigned the `example.com/images/*` route and Worker B is given the `example.com/images*` route pattern. With these in place, here are how the following URLs will be resolved: ```plaintext // (A) example.com/images/* // (B) example.com/images* "example.com/images" // -> B "example.com/images123" // -> B "example.com/images/hello" // -> B ``` You will notice that all examples trigger Worker B. This includes the final example, which exemplifies the unexpected behavior. When adding a wildcard on a subdomain, here are how the following URLs will be resolved: ```plaintext // (A) *.example.com/a // (B) a.example.com/* "a.example.com/a" // -> B ``` ## wrangler dev * When running `wrangler dev --remote`, all outgoing requests are given the `cf-workers-preview-token` header, which Cloudflare recognizes as a preview request. This applies to the entire Cloudflare network, so making HTTP requests to other Cloudflare zones is currently discarded for security reasons. To enable a workaround, insert the following code into your Worker script: ```js const request = new Request(url, incomingRequest); request.headers.delete('cf-workers-preview-token'); return await fetch(request); ``` ## Fetch API in CNAME setup When you make a subrequest using [fetch()](https://66f4ea29.previews.developers.cloudflare.com/workers/runtime-apis/fetch/) from a Worker, the Cloudflare DNS resolver is used. When a zone has a [Partial (CNAME) setup](https://66f4ea29.previews.developers.cloudflare.com/dns/zone-setups/partial-setup/), all hostnames that the Worker needs to be able to resolve require a dedicated DNS entry in Cloudflare's DNS setup. Otherwise the Fetch API call will fail with status code [530 (1016)](https://66f4ea29.previews.developers.cloudflare.com/support/troubleshooting/http-status-codes/cloudflare-1xxx-errors/error-1016/). Setup with missing DNS records in Cloudflare DNS ```plaintext // Zone in partial setup: example.com // DNS records at Authoritative DNS: sub1.example.com, sub2.example.com, ... // DNS records at Cloudflare DNS: sub1.example.com "sub1.example.com/" // -> Can be resolved by Fetch API "sub2.example.com/" // -> Cannot be resolved by Fetch API, will lead to 530 status code ``` After adding `sub2.example.com` to Cloudflare DNS ```plaintext // Zone in partial setup: example.com // DNS records at Authoritative DNS: sub1.example.com, sub2.example.com, ... // DNS records at Cloudflare DNS: sub1.example.com, sub2.example.com "sub1.example.com/" // -> Can be resolved by Fetch API "sub2.example.com/" // -> Can be resolved by Fetch API ``` ## Fetch to IP addresses For Workers subrequests, requests can only be made to URLs, not to IP addresses directly. To overcome this limitation [add a A or AAAA name record to your zone ↗](https://developers.cloudflare.com/dns/manage-dns-records/how-to/create-dns-records/) and then fetch that resource. For example, in the zone `example.com` create a record of type `A` with the name `server` and value `192.0.2.1`, and then use: ```js await fetch('http://server.example.com') ``` Do not use: ```js await fetch('http://192.0.2.1') ``` Was this helpful? YesNo ## On this page [![](https://66f4ea29.previews.developers.cloudflare.com/_astro/logo.te5VL_aD.svg)Docs](https://66f4ea29.previews.developers.cloudflare.com/) ```json {"@context":"https://schema.org","@type":"TechArticle","@id":"https://developers.cloudflare.com/workers/platform/known-issues/#page","headline":"Known issues · Cloudflare Workers docs","description":"Known issues and bugs to be aware of when using Workers.","url":"https://developers.cloudflare.com/workers/platform/known-issues/","inLanguage":"en","image":"https://developers.cloudflare.com/og-docs.png","dateModified":"2026-08-25","publisher":{"@type":"Organization","name":"Cloudflare","description":"One platform for your apps, agents, and workforce. 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