I have the following query that should perform CosineSimilarity: { "query": { "function_score": { "query": { "match_all": {} }, "script_score": { "script": { "source": "cosineSimilarity (params.queryVector, doc[ embedding ) + 1.0", "params": { "queryVector": [-0.0011626648483797908, 0.005565074738115072, ...] } } } } } We use ElasticSearch 7.10.0. I can t pinpoint what the issue is in this test query. From what I know CosineSimilarity should be available in ES 7.10+. The error encountered was: { "error": { "root_cause":[...] "type": "search_phase_execution_exception", "reason": "all shards failed", "phase": "query", "grouped": true, "failed_shards": [...], "script": "cosineSimilarity (params.queryVector, doc[ embedding ]) + 1.0",.. }, "caused_by": { "type": "illegal_argument_exception", "reason": "Unknown call [cosineSimilarity] with [2] arguments." } } } } ], "caused_by": { "type": "script_exception", "reason": "compile error", "script_stack": [ "cosineSimilarity (params. ...", "^---- HERE" ], "script": "cosineSimilarity (params.queryVector, doc[ embedding ]) + 1.0"... "caused_by": { "type": "illegal_argument_exception", "reason": "Unknown call [cosineSimilarity] with [2] arguments." } } }, "status": 400 } Here s the property mapping of the embedding in the index: "embeddings": { "type": "knn_vector", "dimension": 1536 }... I followed the documentation in ES for CosineSimilarity but still encountering this error.