diff --git a/server/src/main/java/org/elasticsearch/cluster/metadata/FieldInferenceMetadata.java b/server/src/main/java/org/elasticsearch/cluster/metadata/FieldInferenceMetadata.java
index 0d02f0aa43db1..08a570b9980dc 100644
--- a/server/src/main/java/org/elasticsearch/cluster/metadata/FieldInferenceMetadata.java
+++ b/server/src/main/java/org/elasticsearch/cluster/metadata/FieldInferenceMetadata.java
@@ -58,6 +58,10 @@ public FieldInferenceMetadata(Map<String, FieldInference> fieldsToInferenceMap)
         fieldInferenceMap = ImmutableOpenMap.builder(fieldsToInferenceMap).build();
     }
 
+    public boolean isEmpty() {
+        return fieldInferenceMap.isEmpty();
+    }
+
     public record FieldInference(String inferenceId, Set<String> sourceFields)
         implements
             SimpleDiffable<FieldInference>,
diff --git a/server/src/main/java/org/elasticsearch/cluster/metadata/IndexMetadata.java b/server/src/main/java/org/elasticsearch/cluster/metadata/IndexMetadata.java
index 1060addd008d1..842edc5bf9f1e 100644
--- a/server/src/main/java/org/elasticsearch/cluster/metadata/IndexMetadata.java
+++ b/server/src/main/java/org/elasticsearch/cluster/metadata/IndexMetadata.java
@@ -734,7 +734,7 @@ private IndexMetadata(
         this.writeLoadForecast = writeLoadForecast;
         this.shardSizeInBytesForecast = shardSizeInBytesForecast;
         assert numberOfShards * routingFactor == routingNumShards : routingNumShards + " must be a multiple of " + numberOfShards;
-        this.fieldInferenceMetadata = fieldInferenceMetadata;
+        this.fieldInferenceMetadata = Objects.requireNonNullElse(fieldInferenceMetadata, FieldInferenceMetadata.EMPTY);
     }
 
     IndexMetadata withMappingMetadata(MappingMetadata mapping) {
@@ -2422,7 +2422,9 @@ public static void toXContent(IndexMetadata indexMetadata, XContentBuilder build
                 builder.field(KEY_SHARD_SIZE_FORECAST, indexMetadata.shardSizeInBytesForecast);
             }
 
-            builder.field(KEY_FIELD_INFERENCE_METADATA, indexMetadata.fieldInferenceMetadata);
+            if (indexMetadata.fieldInferenceMetadata.isEmpty() == false) {
+                builder.field(KEY_FIELD_INFERENCE_METADATA, indexMetadata.fieldInferenceMetadata);
+            }
 
             builder.endObject();
         }