# Inconsistant CORS issues 

**URL:** <https://community.cesium.com/t/inconsistant-cors-issues/42209>\
**Category:** CesiumJS\
**Created:** [July 21, 2025, 12:38pm UTC](https://community.cesium.com/t/inconsistant-cors-issues/42209 "2025-07-21T12:38:35Z")\
**Posts on this page:** 3\
**Page:** 1

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**Author:** ![jinpark](https://sea2.discourse-cdn.com/cesium/user_avatar/community.cesium.com/jinpark/32/14000_2.png) [@jinpark](https://community.cesium.com/u/jinpark)\
**Post date:** [July 21, 2025, 12:38pm UTC](https://community.cesium.com/t/inconsistant-cors-issues/42209/1 "2025-07-21T12:38:35Z")

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I’ve been seeing some inconsistent cors issues when fetching `https://assets.ion.cesium.com/us-east-1/asset_depot/1/CesiumWorldTerrain/v1.2/layer.json` Preflight works fine but actual fetching fails with a CORS error.

 ![image](https://global.discourse-cdn.com/cesium/original/3X/b/4/b4aebb4a6be5bee785f94420dc670ce7a3de29a7.png)

I’m also seeing it in sandcastle’s as well ex. [Cesium Sandcastle](https://sandcastle.cesium.com/?src=Clipping%20Regions.html)

This alert pops up while loading

 ![image](https://global.discourse-cdn.com/cesium/original/3X/0/5/05c2b4fe04096bc7541a5dfff9dc6b12a4af8138.jpeg)

I disabled all extensions to verify and I sometimes see the layer.json file being fetched correctly and when it gets cached, it works fine afterwards.

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**Author:** ![Marco13](https://sea2.discourse-cdn.com/cesium/user_avatar/community.cesium.com/marco13/32/2757_2.png) [@Marco13](https://community.cesium.com/u/Marco13)\
**Post date:** [July 21, 2025, 12:44pm UTC](https://community.cesium.com/t/inconsistant-cors-issues/42209/2 "2025-07-21T12:44:09Z")

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To have a cross-link: This seems to the the same as [Cesium World Terrain is making the globe "half empty"](https://community.cesium.com/t/cesium-world-terrain-is-making-the-globe-half-empty/42206)

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**Author:** ![Ankit\_Trehan](https://sea2.discourse-cdn.com/cesium/user_avatar/community.cesium.com/ankit_trehan/32/14038_2.png) [@Ankit\_Trehan](https://community.cesium.com/u/Ankit_Trehan)\
**Post date:** [July 21, 2025, 1:58pm UTC](https://community.cesium.com/t/inconsistant-cors-issues/42209/3 "2025-07-21T13:58:53Z")

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Hi,

Thank you for reporting this behavior. We are aware of this issue and are actively working on fixing it. We had an issue with some of our data products. While that issue has been resolved, there may be some old cached requests in our CDN serving stale requests. We are working on invalidating those cached requests.

Thanks,  
Ankit