# JSON Cors

**URL:** <https://talk.observablehq.com/t/json-cors/2259>\
**Category:** Help\
**Created:** [August 13, 2019, 12:00pm UTC](https://talk.observablehq.com/t/json-cors/2259 "2019-08-13T12:00:53Z")\
**Posts on this page:** 3\
**Page:** 1

<div class="post-metadata">

**Author:** ![cjfpainter](https://yyz2.discourse-cdn.com/flex030/user_avatar/talk.observablehq.com/cjfpainter/32/926_2.png) [@cjfpainter](https://talk.observablehq.com/u/cjfpainter)\
**Post date:** [August 13, 2019, 12:00pm UTC](https://talk.observablehq.com/t/json-cors/2259/1 "2019-08-13T12:00:53Z")

</div>

My notebooks access JSON data from a node/express setup which has Cors enabled ( [sherlock.scalingo.io](http://sherlock.scalingo.io) ). Curiously some notebooks work ( [https://observablehq.com/@cjfpainter/idea-mining-the-mueller-report?collection=@cjfpainter/my-public](https://observablehq.com/@cjfpainter/idea-mining-the-mueller-report?collection=@cjfpainter/my-public) ), whereas others which used to now don’t and give errors like this.

`Access to fetch at 'https://sherlock.scalingo.io/headstart_find_keys?search=*' from origin 'https://cjfpainter.static.observableusercontent.com' has been blocked by CORS policy: No 'Access-Control-Allow-Origin' header is present on the requested resource. If an opaque response serves your needs, set the request's mode to 'no-cors' to fetch the resource with CORS disabled.`

I’ve checked the server code and rebooted, but remain baffled. All was well until about an hour ago from now 2019-08-12T23:00:00Z.

---

<div class="post-metadata">

**Author:** ![bgchen](https://yyz2.discourse-cdn.com/flex030/user_avatar/talk.observablehq.com/bgchen/32/784_2.png) [@bgchen](https://talk.observablehq.com/u/bgchen)\
**Post date:** [August 13, 2019, 1:07pm UTC](https://talk.observablehq.com/t/json-cors/2259/2 "2019-08-13T13:07:22Z")

</div>

Could you share a link to a notebook where you reliably get CORS errors?

---

<div class="post-metadata">

**Author:** ![cjfpainter](https://yyz2.discourse-cdn.com/flex030/user_avatar/talk.observablehq.com/cjfpainter/32/926_2.png) [@cjfpainter](https://talk.observablehq.com/u/cjfpainter)\
**Post date:** [August 13, 2019, 4:02pm UTC](https://talk.observablehq.com/t/json-cors/2259/3 "2019-08-13T16:02:21Z")

</div>

Hi there, genuine thanks for replying, but now the problem has gone away! Leaves me happier, a little more informed on CORS, and a bit embarrassed for calling you out in vain! My thanks and apologies therefore.