# Unable to verify that the server is ElasticSearch due to unsuccesful product check call
**URL:** https://discuss.elastic.co/t/unable-to-verify-that-the-server-is-elasticsearch-due-to-unsuccesful-product-check-call/308000
**Category:** Elasticsearch
**Tags:** language-clients
**Created:** [June 23, 2022, 11:58am UTC](https://discuss.elastic.co/t/unable-to-verify-that-the-server-is-elasticsearch-due-to-unsuccesful-product-check-call/308000 "2022-06-23T11:58:01Z")
**Posts on this page:** 4
**Page:** 1
### Author:  [@charlot\_Attard](https://discuss.elastic.co/u/charlot_Attard)
#### Post date: [June 23, 2022, 11:58am UTC](https://discuss.elastic.co/t/unable-to-verify-that-the-server-is-elasticsearch-due-to-unsuccesful-product-check-call/308000/1 "2022-06-23T11:58:01Z")
Hello,
We have an application connecting with NEST to ES Version 7.17. Intermitently we are facing this issue
Unable to verify that the server is ElasticSearch due to unsuccesful product check call. Some functionality may not be compatible if the server is running an unsupported product. Call: Status code unkown from: GET /
We did manual curl from the microservice and all of them were successful
Any idea what could be wrong ?
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### Author:  [@stevejgordon](https://discuss.elastic.co/u/stevejgordon)
#### Post date: [June 23, 2022, 12:54pm UTC](https://discuss.elastic.co/t/unable-to-verify-that-the-server-is-elasticsearch-due-to-unsuccesful-product-check-call/308000/2 "2022-06-23T12:54:57Z")
Hi, @charlot_Attard,
On the first request, the client performs a product check to verify a compatible server. If for any reason the server response fails, we add this warning to the debug information. Is there where you are seeing it? We will attempt to verify the next requests until we have successfully validated the server. The most likely cause is transient network issue.
Are you reusing the same `ElasticClient` instance? Once the first requests succeeds, you should no longer receive the warning on subsequent requests.
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### Author:  [@charlot\_Attard](https://discuss.elastic.co/u/charlot_Attard)
#### Post date: [June 23, 2022, 1:20pm UTC](https://discuss.elastic.co/t/unable-to-verify-that-the-server-is-elasticsearch-due-to-unsuccesful-product-check-call/308000/3 "2022-06-23T13:20:31Z")
Thanks for your reply.
Please note that ES is logging this as an Error. The issue is intermittent so when the application which uses NEST client connects with ES sometimes it does return this error and sometimes it does work.
This is a 5 node cluster, and I don't have an idea if the application tries to reuse the same node it connect to. I don't think it does.
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### Author:  [@system](https://discuss.elastic.co/u/system)
#### Post date: [July 21, 2022, 1:21pm UTC](https://discuss.elastic.co/t/unable-to-verify-that-the-server-is-elasticsearch-due-to-unsuccesful-product-check-call/308000/4 "2022-07-21T13:21:30Z")
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