# The client noticed that the server is not a supported distribution of Elasticsearch or an unknown product

**URL:** <https://discuss.elastic.co/t/the-client-noticed-that-the-server-is-not-a-supported-distribution-of-elasticsearch-or-an-unknown-product/380535>\
**Category:** Elastic Search\
**Created:** [July 29, 2025, 11:06am UTC](https://discuss.elastic.co/t/the-client-noticed-that-the-server-is-not-a-supported-distribution-of-elasticsearch-or-an-unknown-product/380535 "2025-07-29T11:06:40Z")\
**Posts on this page:** 2\
**Page:** 1

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**Author:** ![Arun\_VR](https://sea2.discourse-cdn.com/elastic/user_avatar/discuss.elastic.co/arun_vr/32/144362_2.png) [@Arun\_VR](https://discuss.elastic.co/u/Arun_VR)\
**Post date:** [July 29, 2025, 11:06am UTC](https://discuss.elastic.co/t/the-client-noticed-that-the-server-is-not-a-supported-distribution-of-elasticsearch-or-an-unknown-product/380535/1 "2025-07-29T11:06:40Z")

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**Hi Team,**

I have a .NET project that was previously using the following Elasticsearch setup:

- **Version:** 7.12.0
- **Lucene Version:** 8.8.0
- **Minimum Wire Compatibility Version:** 6.8.0
- **Minimum Index Compatibility Version:** 6.0.0-beta1

Recently, I upgraded the project from **.NET Framework to .NET Core**.  
It uses **Elastic.Clients.Elasticsearch Version 8.17.3**

Now, when I try to create a new index using the **same Elasticsearch account** , I encounter this error:

```auto
The client noticed that the server is not a supported distribution of Elasticsearch or an unknown product.

```

However, after logging into Elasticsearch, I noticed that the index does get created, but it **doesn't work due to compatibility issues**.

### My question:

**Would upgrading the old Elasticsearch instance solve this issue without changing the code?**

Any help is appreciated.

Thanks in advance!

---

<div class="post-metadata">

**Author:** ![JD\_Armada](https://sea2.discourse-cdn.com/elastic/user_avatar/discuss.elastic.co/jd_armada/32/142652_2.png) [@JD\_Armada](https://discuss.elastic.co/u/JD_Armada)\
**Post date:** [July 29, 2025, 11:09pm UTC](https://discuss.elastic.co/t/the-client-noticed-that-the-server-is-not-a-supported-distribution-of-elasticsearch-or-an-unknown-product/380535/2 "2025-07-29T23:09:34Z")

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Hey @Arun_VR,

Welcome to the community!

Starting with version 8.x, the .NET client performs a check for a specific HTTP header that the previous versions don't provide which can trigger the error you're seeing. Upgrading your Elasticsearch cluster should fix this without having to change any of your current implementation. If you're using a non-Elastic fork, the client will still reject it even if you upgrade.

Check out the [Upgrade Assistant](https://www.elastic.co/docs/deploy-manage/upgrade/prepare-to-upgrade/upgrade-assistant) to make sure everything goes smoothly and read through the Elasticsearch .NET client [readme](https://github.com/elastic/elasticsearch-net) to see information about backwards and forward compatibility as well as any potential breaking changes.

Hope this helps, let us know how it goes!