diff --git a/afs-ws/afs-ws-client-utils/src/main/java/com/powsybl/afs/ws/client/utils/ClientUtils.java b/afs-ws/afs-ws-client-utils/src/main/java/com/powsybl/afs/ws/client/utils/ClientUtils.java
index 12bc8800..3fc80f66 100644
--- a/afs-ws/afs-ws-client-utils/src/main/java/com/powsybl/afs/ws/client/utils/ClientUtils.java
+++ b/afs-ws/afs-ws-client-utils/src/main/java/com/powsybl/afs/ws/client/utils/ClientUtils.java
@@ -93,7 +93,6 @@ public static <T> T readEntityIfOk(Response response, Class<T> entityType) {
         } else {
             throw createUnexpectedResponseStatus(status);
         }
-
     }
 
     public static <T> T readEntityIfOk(Response response, GenericType<T> entityType) {
@@ -114,16 +113,11 @@ public static <T> T readEntityIfOk(Response response, GenericType<T> entityType)
 
     public static <T> Optional<T> readOptionalEntityIfOk(Response response, Class<T> entityType) {
         Response.Status status = Response.Status.fromStatusCode(response.getStatus());
-        if (status == Response.Status.OK) {
-            return Optional.of(readEntityAndLog(response, entityType));
-        } else if (status == Response.Status.NO_CONTENT) {
+        if (status == Response.Status.NO_CONTENT || status == Response.Status.NOT_FOUND) {
             LOGGER.trace("    --> null");
             return Optional.empty();
-        } else if (status == Response.Status.INTERNAL_SERVER_ERROR) {
-            throw createServerErrorException(response);
-        } else {
-            throw createUnexpectedResponseStatus(status);
         }
+        return Optional.of(readEntityIfOk(response, entityType));
     }
 
     public static UserSession authenticate(URI baseUri, String login, String password) {
diff --git a/afs-ws/afs-ws-server/src/main/java/com/powsybl/afs/ws/server/AppStorageServer.java b/afs-ws/afs-ws-server/src/main/java/com/powsybl/afs/ws/server/AppStorageServer.java
index 18df54d6..2d3f2cf1 100644
--- a/afs-ws/afs-ws-server/src/main/java/com/powsybl/afs/ws/server/AppStorageServer.java
+++ b/afs-ws/afs-ws-server/src/main/java/com/powsybl/afs/ws/server/AppStorageServer.java
@@ -13,8 +13,8 @@
 import com.powsybl.afs.storage.NodeGenericMetadata;
 import com.powsybl.afs.storage.NodeInfo;
 import com.powsybl.afs.storage.buffer.*;
-import com.powsybl.afs.ws.server.utils.JwtTokenNeeded;
 import com.powsybl.afs.ws.server.utils.AppDataBean;
+import com.powsybl.afs.ws.server.utils.JwtTokenNeeded;
 import com.powsybl.afs.ws.utils.AfsRestApi;
 import com.powsybl.afs.ws.utils.gzip.Compress;
 import com.powsybl.timeseries.DoubleDataChunk;
@@ -109,7 +109,7 @@ public Response createNode(@ApiParam(value = "File system name") @PathParam("fil
                                @ApiParam(value = "Version") @QueryParam("version") int version,
                                @ApiParam(value = "Node Meta Data") NodeGenericMetadata nodeMetadata) {
         AppStorage storage = appDataBean.getStorage(fileSystemName);
-        NodeInfo newNodeInfo =  storage.createNode(nodeId, childName, nodePseudoClass, description, version, nodeMetadata);
+        NodeInfo newNodeInfo = storage.createNode(nodeId, childName, nodePseudoClass, description, version, nodeMetadata);
         return Response.ok().entity(newNodeInfo).build();
     }
 
@@ -138,7 +138,7 @@ public Response getParentNode(@ApiParam(value = "File system name") @PathParam("
         if (parentNodeInfo.isPresent()) {
             return Response.ok().entity(parentNodeInfo.get()).build();
         } else {
-            return Response.noContent().build();
+            return Response.status(Status.NOT_FOUND).build();
         }
     }
 
@@ -155,7 +155,7 @@ public Response getChildNode(@ApiParam(value = "File system name") @PathParam("f
         if (childNodeInfo.isPresent()) {
             return Response.status(Status.OK).entity(childNodeInfo.get()).build();
         } else {
-            return Response.status(Status.NO_CONTENT).build();
+            return Response.status(Status.NOT_FOUND).build();
         }
     }