diff --git a/src/main/java/org/opensearch/knn/index/query/KNNQueryBuilder.java b/src/main/java/org/opensearch/knn/index/query/KNNQueryBuilder.java
index 61ffc567e..bab0b2519 100644
--- a/src/main/java/org/opensearch/knn/index/query/KNNQueryBuilder.java
+++ b/src/main/java/org/opensearch/knn/index/query/KNNQueryBuilder.java
@@ -44,6 +44,7 @@
 import java.io.IOException;
 import java.util.Arrays;
 import java.util.List;
+import java.util.Locale;
 import java.util.Map;
 import java.util.Objects;
 
@@ -199,33 +200,38 @@ public KNNQueryBuilder build() {
 
         private void validate() {
             if (Strings.isNullOrEmpty(fieldName)) {
-                throw new IllegalArgumentException(String.format("[%s] requires fieldName", NAME));
+                throw new IllegalArgumentException(String.format(Locale.ROOT, "[%s] requires fieldName", NAME));
             }
 
             if (vector == null) {
-                throw new IllegalArgumentException(String.format("[%s] requires query vector", NAME));
+                throw new IllegalArgumentException(String.format(Locale.ROOT, "[%s] requires query vector", NAME));
             } else if (vector.length == 0) {
-                throw new IllegalArgumentException(String.format("[%s] query vector is empty", NAME));
+                throw new IllegalArgumentException(String.format(Locale.ROOT, "[%s] query vector is empty", NAME));
             }
 
             if (k == null && minScore == null && maxDistance == null) {
-                throw new IllegalArgumentException(String.format("[%s] requires exactly one of k, distance or score to be set", NAME));
+                throw new IllegalArgumentException(
+                    String.format(Locale.ROOT, "[%s] requires exactly one of k, distance or score to be set", NAME)
+                );
             }
 
             if ((k != null && maxDistance != null) || (maxDistance != null && minScore != null) || (k != null && minScore != null)) {
-                throw new IllegalArgumentException(String.format("[%s] requires exactly one of k, distance or score to be set", NAME));
+                throw new IllegalArgumentException(
+                    String.format(Locale.ROOT, "[%s] requires exactly one of k, distance or score to be set", NAME)
+                );
             }
 
             if (k != null) {
                 if (k <= 0 || k > K_MAX) {
-                    final String errorMessage = "[" + NAME + "] requires k to be in the range (0, " + K_MAX + "]";
-                    throw new IllegalArgumentException(errorMessage);
+                    throw new IllegalArgumentException(
+                        String.format(Locale.ROOT, "[%s] requires k to be in the range (0, %d]", NAME, K_MAX)
+                    );
                 }
             }
 
             if (minScore != null) {
                 if (minScore <= 0) {
-                    throw new IllegalArgumentException(String.format("[%s] requires minScore to be greater than 0", NAME));
+                    throw new IllegalArgumentException(String.format(Locale.ROOT, "[%s] requires minScore to be greater than 0", NAME));
                 }
             }
 
@@ -233,7 +239,7 @@ private void validate() {
                 ValidationException validationException = validateMethodParameters(methodParameters);
                 if (validationException != null) {
                     throw new IllegalArgumentException(
-                        String.format("[%s] errors in method parameter [%s]", NAME, validationException.getMessage())
+                        String.format(Locale.ROOT, "[%s] errors in method parameter [%s]", NAME, validationException.getMessage())
                     );
                 }
             }
@@ -259,19 +265,19 @@ public KNNQueryBuilder(String fieldName, float[] vector, int k) {
     @Deprecated
     public KNNQueryBuilder(String fieldName, float[] vector, int k, QueryBuilder filter) {
         if (Strings.isNullOrEmpty(fieldName)) {
-            throw new IllegalArgumentException(String.format("[%s] requires fieldName", NAME));
+            throw new IllegalArgumentException(String.format(Locale.ROOT, "[%s] requires fieldName", NAME));
         }
         if (vector == null) {
-            throw new IllegalArgumentException(String.format("[%s] requires query vector", NAME));
+            throw new IllegalArgumentException(String.format(Locale.ROOT, "[%s] requires query vector", NAME));
         }
         if (vector.length == 0) {
-            throw new IllegalArgumentException(String.format("[%s] query vector is empty", NAME));
+            throw new IllegalArgumentException(String.format(Locale.ROOT, "[%s] query vector is empty", NAME));
         }
         if (k <= 0) {
-            throw new IllegalArgumentException(String.format("[%s] requires k > 0", NAME));
+            throw new IllegalArgumentException(String.format(Locale.ROOT, "[%s] requires k > 0", NAME));
         }
         if (k > K_MAX) {
-            throw new IllegalArgumentException(String.format("[%s] requires k <= %d", NAME, K_MAX));
+            throw new IllegalArgumentException(String.format(Locale.ROOT, "[%s] requires k <= %d", NAME, K_MAX));
         }
 
         this.fieldName = fieldName;
@@ -289,12 +295,16 @@ public static void initialize(ModelDao modelDao) {
 
     private static float[] ObjectsToFloats(List<Object> objs) {
         if (Objects.isNull(objs) || objs.isEmpty()) {
-            throw new IllegalArgumentException(String.format("[%s] field 'vector' requires to be non-null and non-empty", NAME));
+            throw new IllegalArgumentException(
+                String.format(Locale.ROOT, "[%s] field 'vector' requires to be non-null and non-empty", NAME)
+            );
         }
         float[] vec = new float[objs.size()];
         for (int i = 0; i < objs.size(); i++) {
             if ((objs.get(i) instanceof Number) == false) {
-                throw new IllegalArgumentException(String.format("[%s] field 'vector' requires to be an array of numbers", NAME));
+                throw new IllegalArgumentException(
+                    String.format(Locale.ROOT, "[%s] field 'vector' requires to be an array of numbers", NAME)
+                );
             }
             vec[i] = ((Number) objs.get(i)).floatValue();
         }
@@ -511,7 +521,7 @@ protected Query doToQuery(QueryShardContext context) {
         }
 
         if (!(mappedFieldType instanceof KNNVectorFieldMapper.KNNVectorFieldType)) {
-            throw new IllegalArgumentException(String.format("Field '%s' is not knn_vector type.", this.fieldName));
+            throw new IllegalArgumentException(String.format(Locale.ROOT, "Field '%s' is not knn_vector type.", this.fieldName));
         }
 
         KNNVectorFieldMapper.KNNVectorFieldType knnVectorFieldType = (KNNVectorFieldMapper.KNNVectorFieldType) mappedFieldType;
@@ -553,6 +563,7 @@ protected Query doToQuery(QueryShardContext context) {
             if (validationException != null) {
                 throw new IllegalArgumentException(
                     String.format(
+                        Locale.ROOT,
                         "Parameters not valid for [%s]:[%s]:[%s] combination: [%s]",
                         knnEngine,
                         method,
@@ -605,7 +616,7 @@ protected Query doToQuery(QueryShardContext context) {
         if (KNNEngine.getEnginesThatCreateCustomSegmentFiles().contains(knnEngine)
             && filter != null
             && !KNNEngine.getEnginesThatSupportsFilters().contains(knnEngine)) {
-            throw new IllegalArgumentException(String.format("Engine [%s] does not support filters", knnEngine));
+            throw new IllegalArgumentException(String.format(Locale.ROOT, "Engine [%s] does not support filters", knnEngine));
         }
 
         String indexName = context.index().getName();
@@ -627,7 +638,9 @@ protected Query doToQuery(QueryShardContext context) {
         }
         if (radius != null) {
             if (!ENGINES_SUPPORTING_RADIAL_SEARCH.contains(knnEngine)) {
-                throw new UnsupportedOperationException(String.format("Engine [%s] does not support radial search", knnEngine));
+                throw new UnsupportedOperationException(
+                    String.format(Locale.ROOT, "Engine [%s] does not support radial search", knnEngine)
+                );
             }
             RNNQueryFactory.CreateQueryRequest createQueryRequest = RNNQueryFactory.CreateQueryRequest.builder()
                 .knnEngine(knnEngine)
@@ -643,19 +656,19 @@ protected Query doToQuery(QueryShardContext context) {
                 .build();
             return RNNQueryFactory.create(createQueryRequest);
         }
-        throw new IllegalArgumentException(String.format("[%s] requires k or distance or score to be set", NAME));
+        throw new IllegalArgumentException(String.format(Locale.ROOT, "[%s] requires k or distance or score to be set", NAME));
     }
 
     private ModelMetadata getModelMetadataForField(KNNVectorFieldMapper.KNNVectorFieldType knnVectorField) {
         String modelId = knnVectorField.getModelId();
 
         if (modelId == null) {
-            throw new IllegalArgumentException(String.format("Field '%s' does not have model.", this.fieldName));
+            throw new IllegalArgumentException(String.format(Locale.ROOT, "Field '%s' does not have model.", this.fieldName));
         }
 
         ModelMetadata modelMetadata = modelDao.getMetadata(modelId);
         if (!ModelUtil.isModelCreated(modelMetadata)) {
-            throw new IllegalArgumentException(String.format("Model ID '%s' is not created.", modelId));
+            throw new IllegalArgumentException(String.format(Locale.ROOT, "Model ID '%s' is not created.", modelId));
         }
         return modelMetadata;
     }
@@ -677,7 +690,7 @@ private VectorQueryType getVectorQueryType(int k, Float maxDistance, Float minSc
         if (k != 0) {
             return VectorQueryType.K;
         }
-        throw new IllegalArgumentException(String.format("[%s] requires exactly one of k, distance or score to be set", NAME));
+        throw new IllegalArgumentException(String.format(Locale.ROOT, "[%s] requires exactly one of k, distance or score to be set", NAME));
     }
 
     /**