# Error: BadRequestError(400, 'parsing\_exception', 'Unknown key for a START\_OBJECT in \[knn\].')

**URL:** <https://discuss.elastic.co/t/error-badrequesterror-400-parsing-exception-unknown-key-for-a-start-object-in-knn/358551>\
**Category:** Elastic Search\
**Created:** [May 1, 2024, 10:47am UTC](https://discuss.elastic.co/t/error-badrequesterror-400-parsing-exception-unknown-key-for-a-start-object-in-knn/358551 "2024-05-01T10:47:13Z")\
**Posts on this page:** 4\
**Page:** 1

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**Author:** ![Sharmishtha\_Paliwal](https://sea2.discourse-cdn.com/elastic/user_avatar/discuss.elastic.co/sharmishtha_paliwal/32/122545_2.png) [@Sharmishtha\_Paliwal](https://discuss.elastic.co/u/Sharmishtha_Paliwal)\
**Post date:** [May 1, 2024, 10:47am UTC](https://discuss.elastic.co/t/error-badrequesterror-400-parsing-exception-unknown-key-for-a-start-object-in-knn/358551/1 "2024-05-01T10:47:13Z")

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I am not able to figure to this issue  
response = es.search(index="cv\_resume\_dense",query= {  
"match": {  
"work\_experience": {  
"query": query,  
"boost": 0.9  
},  
},  
},  
knn= {  
"field": "vector\_skills",  
"query\_vector": query\_vector,  
"k": 5,  
"num\_candidates": 50,  
"boost": 0.1  
},  
size= 10)

---

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**Author:** ![Kathleen\_DeRusso](https://sea2.discourse-cdn.com/elastic/user_avatar/discuss.elastic.co/kathleen_derusso/32/132039_2.png) [@Kathleen\_DeRusso](https://discuss.elastic.co/u/Kathleen_DeRusso)\
**Post date:** [May 1, 2024, 12:19pm UTC](https://discuss.elastic.co/t/error-badrequesterror-400-parsing-exception-unknown-key-for-a-start-object-in-knn/358551/2 "2024-05-01T12:19:40Z")

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If you're using \>= 8.12, try using knn as a query rather than a top level argument. Here's an [example](https://www.elastic.co/guide/en/elasticsearch/reference/current/query-dsl-knn-query.html#knn-query-in-hybrid-search) of how you can achieve this type of hybrid search using a boolean query.

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**Author:** ![joemcelroy](https://sea2.discourse-cdn.com/elastic/user_avatar/discuss.elastic.co/joemcelroy/32/103757_2.png) [@joemcelroy](https://discuss.elastic.co/u/joemcelroy)\
**Post date:** [May 1, 2024, 2:42pm UTC](https://discuss.elastic.co/t/error-badrequesterror-400-parsing-exception-unknown-key-for-a-start-object-in-knn/358551/3 "2024-05-01T14:42:10Z")

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Also this python notebook might help. Double check the version of your client. I suspect your version of your client isn't 8.x.

Search [elasticsearch-labs/notebooks/search/00-quick-start.ipynb at main · elastic/elasticsearch-labs · GitHub](https://github.com/elastic/elasticsearch-labs/blob/main/notebooks/search/00-quick-start.ipynb)

Hybrid [elasticsearch-labs/notebooks/search/02-hybrid-search.ipynb at main · elastic/elasticsearch-labs · GitHub](https://github.com/elastic/elasticsearch-labs/blob/main/notebooks/search/02-hybrid-search.ipynb)

Joe

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**Author:** ![system](https://us1.discourse-cdn.com/elastic/original/3X/1/a/1ac57faf039f6b580b3f104ef42a2a89e41014de.png) [@system](https://discuss.elastic.co/u/system)\
**Post date:** [May 29, 2024, 2:42pm UTC](https://discuss.elastic.co/t/error-badrequesterror-400-parsing-exception-unknown-key-for-a-start-object-in-knn/358551/4 "2024-05-29T14:42:25Z")

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