diff --git a/qa/rolling-upgrade/src/javaRestTest/java/org/elasticsearch/upgrades/DenseVectorRollingUpgradeIT.java b/qa/rolling-upgrade/src/javaRestTest/java/org/elasticsearch/upgrades/DenseVectorRollingUpgradeIT.java
index 8fccb916396cb..c17c249054838 100644
--- a/qa/rolling-upgrade/src/javaRestTest/java/org/elasticsearch/upgrades/DenseVectorRollingUpgradeIT.java
+++ b/qa/rolling-upgrade/src/javaRestTest/java/org/elasticsearch/upgrades/DenseVectorRollingUpgradeIT.java
@@ -26,6 +26,7 @@
 import java.util.Collection;
 import java.util.List;
 import java.util.OptionalInt;
+import java.util.stream.Collectors;
 import java.util.stream.IntStream;
 
 import static org.elasticsearch.rest.action.search.RestSearchAction.TOTAL_HITS_AS_INT_PARAM;
@@ -33,7 +34,7 @@
 
 public class DenseVectorRollingUpgradeIT extends AbstractRollingUpgradeTestCase {
 
-    private static String generateBulkData(int upgradedNodes, int dimensions) {
+    private static String generateBulkData(ElementType elementType, int upgradedNodes, int dimensions) {
         StringBuilder sb = new StringBuilder();
 
         int[] vals = new int[dimensions];
@@ -44,10 +45,16 @@ private static String generateBulkData(int upgradedNodes, int dimensions) {
 
         for (var it = docs.iterator(); it.hasNext();) {
             vals[upgradedNodes]++;
+            // ensure float values are added as floats
+            // so ES doesn't get confused in the mapping
+            String vector = switch (elementType) {
+                case BYTE, BIT -> Arrays.toString(vals);
+                case FLOAT, BFLOAT16 -> Arrays.stream(vals).mapToObj(i -> i + ".0").collect(Collectors.joining(",", "[", "]"));
+            };
 
             sb.append("{\"index\": {\"_id\": \"").append(it.nextInt()).append("\"}}");
             sb.append(System.lineSeparator());
-            sb.append("{\"embedding\": ").append(Arrays.toString(vals)).append("}");
+            sb.append("{\"embedding\": ").append(vector).append("}");
             sb.append(System.lineSeparator());
         }
 
@@ -95,7 +102,7 @@ public void testDenseVectorMappingUpdateOnOldCluster() throws IOException {
             client().performRequest(createIndex);
             Request index = new Request("POST", "/" + indexName + "/_bulk/");
             index.addParameter("refresh", "true");
-            index.setJsonEntity(generateBulkData(upgradedNodes, 8));
+            index.setJsonEntity(generateBulkData(ElementType.FLOAT, upgradedNodes, 8));
             client().performRequest(index);
         }
 
@@ -125,7 +132,7 @@ public void testDenseVectorMappingUpdateOnOldCluster() throws IOException {
             assertOK(client().performRequest(updateMapping));
             Request index = new Request("POST", "/" + indexName + "/_bulk/");
             index.addParameter("refresh", "true");
-            index.setJsonEntity(generateBulkData(upgradedNodes, 8));
+            index.setJsonEntity(generateBulkData(ElementType.FLOAT, upgradedNodes, 8));
             assertOK(client().performRequest(index));
             expectedCount = 20;
             assertCount(indexName, expectedCount);
@@ -214,7 +221,7 @@ public void testDenseVectorIndexOverUpgrade() throws IOException {
 
                     Request index = new Request("POST", "/" + indexName + "/_bulk/");
                     index.addParameter("refresh", "true");
-                    index.setJsonEntity(generateBulkData(upgradedNodes, dims.getAsInt()));
+                    index.setJsonEntity(generateBulkData(elementType, upgradedNodes, dims.getAsInt()));
                     assertOK(client().performRequest(index));
 
                     int count = existingCount + 10;