diff --git a/CHANGELOG.md b/CHANGELOG.md
index 05b5643fa..3b51e0600 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -10,6 +10,7 @@ All notable changes to AET will be documented in this file.
 ## Unreleased
 
 **List of changes that are finished but not yet released in any final version.**
+- [PR-469](https://github.com/Cognifide/aet/pull/469) Fix WebAPI issues([#425](https://github.com/Cognifide/aet/issues/425)) 
 - [PR-439](https://github.com/Cognifide/aet/pull/439) Fixed duplicating line and column numbers in accessibility tab
 - [PR-360](https://github.com/Cognifide/aet/pull/360) Keyboard shortcuts for 'Accept/Revert url/test' buttons ([#317](https://github.com/Cognifide/aet/issues/317))
 - [PR-432](https://github.com/Cognifide/aet/pull/432) Fixed issue with lack of clear message for erroneous suite definition.
diff --git a/core/datastorage/src/main/java/com/cognifide/aet/vs/artifacts/ArtifactsDAOMongoDBImpl.java b/core/datastorage/src/main/java/com/cognifide/aet/vs/artifacts/ArtifactsDAOMongoDBImpl.java
index 6c3afba8a..f8be7b332 100644
--- a/core/datastorage/src/main/java/com/cognifide/aet/vs/artifacts/ArtifactsDAOMongoDBImpl.java
+++ b/core/datastorage/src/main/java/com/cognifide/aet/vs/artifacts/ArtifactsDAOMongoDBImpl.java
@@ -98,10 +98,12 @@ public Artifact getArtifact(DBKey dbKey, String objectID) {
 
     GridFS gfs = getGridFS(dbKey);
     BasicDBObject query = new BasicDBObject();
-    query.put(ID_FIELD_NAME, new ObjectId(objectID));
-    GridFSDBFile file = gfs.findOne(query);
-    if (file != null) {
-      artifact = new Artifact(file.getInputStream(), file.getContentType());
+    if (ObjectId.isValid(objectID)) {
+      query.put(ID_FIELD_NAME, new ObjectId(objectID));
+      GridFSDBFile file = gfs.findOne(query);
+      if (file != null) {
+        artifact = new Artifact(file.getInputStream(), file.getContentType());
+      }
     }
     return artifact;
   }
diff --git a/rest-endpoint/src/main/java/com/cognifide/aet/rest/ArtifactServlet.java b/rest-endpoint/src/main/java/com/cognifide/aet/rest/ArtifactServlet.java
index a20cf2520..320e54821 100644
--- a/rest-endpoint/src/main/java/com/cognifide/aet/rest/ArtifactServlet.java
+++ b/rest-endpoint/src/main/java/com/cognifide/aet/rest/ArtifactServlet.java
@@ -50,11 +50,10 @@ protected void process(DBKey dbKey, HttpServletRequest req, HttpServletResponse
     String id = req.getParameter(Helper.ID_PARAM);
     resp.setCharacterEncoding("UTF-8");
     Artifact artifact = artifactsDAO.getArtifact(dbKey, id);
-    artifactsDAO.getArtifact(dbKey, id);
     if (artifact != null) {
       sendArtifact(req, resp, artifact);
     } else {
-      sendErrorMessage(dbKey, resp, id);
+      sendNotFoundMessage(dbKey, resp, id);
     }
   }
 
@@ -70,12 +69,12 @@ private void sendArtifact(HttpServletRequest req, HttpServletResponse resp, Arti
     output.flush();
   }
 
-  private void sendErrorMessage(DBKey dbKey, HttpServletResponse resp, String id)
+  private void sendNotFoundMessage(DBKey dbKey, HttpServletResponse resp, String id)
       throws IOException {
-    resp.setStatus(HttpURLConnection.HTTP_BAD_REQUEST);
+    resp.setStatus(HttpURLConnection.HTTP_NOT_FOUND);
     resp.setContentType("application/json");
     resp.getWriter().write(
-        responseAsJson(GSON, "Unable to get artifact with id : %s form %s", id, dbKey.toString()));
+        responseAsJson(GSON, "Unable to get artifact with id: %s for %s", id, dbKey.toString()));
   }
 
   @Override
diff --git a/rest-endpoint/src/main/java/com/cognifide/aet/rest/ConfigsServlet.java b/rest-endpoint/src/main/java/com/cognifide/aet/rest/ConfigsServlet.java
index 218930078..e3fbd8b8e 100644
--- a/rest-endpoint/src/main/java/com/cognifide/aet/rest/ConfigsServlet.java
+++ b/rest-endpoint/src/main/java/com/cognifide/aet/rest/ConfigsServlet.java
@@ -45,6 +45,8 @@ public class ConfigsServlet extends HttpServlet {
 
   private static final Logger LOGGER = LoggerFactory.getLogger(ConfigsServlet.class);
 
+  private static final Gson GSON = new Gson();
+
   public static final String LOCKS_PARAM = "locks";
 
   public static final String LIST_PARAM = "list";
@@ -82,7 +84,7 @@ protected void doGet(HttpServletRequest req, HttpServletResponse resp) {
 
       if (COMMUNICATION_SETTINGS_PARAM.equals(configType)) {
         CommunicationSettings communicationSettings = new CommunicationSettings(reportDomain);
-        responseWriter.write(new Gson().toJson(communicationSettings));
+        responseWriter.write(GSON.toJson(communicationSettings));
       } else if (LIST_PARAM.equals(configType)) {
         resp.setContentType("text/html; charset=utf-8");
         resp.setHeader("User-Agent",
@@ -121,7 +123,7 @@ private void flushResponseBuffer(HttpServletRequest req, HttpServletResponse res
   }
 
   private String getLocks() {
-    return lockService.getAllLocks().toString();
+    return GSON.toJson(lockService.getAllLocks());
   }
 
   @Override
diff --git a/rest-endpoint/src/main/java/com/cognifide/aet/rest/MetadataServlet.java b/rest-endpoint/src/main/java/com/cognifide/aet/rest/MetadataServlet.java
index d6fbfbaea..2cf90e5a1 100644
--- a/rest-endpoint/src/main/java/com/cognifide/aet/rest/MetadataServlet.java
+++ b/rest-endpoint/src/main/java/com/cognifide/aet/rest/MetadataServlet.java
@@ -108,9 +108,7 @@ protected void process(DBKey dbKey, HttpServletRequest req, HttpServletResponse
       resp.setContentType("application/json");
       resp.getWriter().write(result);
     } else {
-      resp.setStatus(HttpURLConnection.HTTP_BAD_REQUEST);
-      resp.getWriter()
-          .write(responseAsJson(GSON,"Unable to get Suite Metadata for %s", dbKey.toString()));
+      createNotFoundResponse(resp, correlationId, suiteName, suiteVersion, dbKey);
     }
   }
 
@@ -192,6 +190,21 @@ private void checkLock(String suiteIdentifier) throws AETException {
     }
   }
 
+  private void createNotFoundResponse(HttpServletResponse response, String correlationId, String suiteName, String suiteVersion, DBKey dbKey) throws IOException {
+    response.setStatus(HttpURLConnection.HTTP_NOT_FOUND);
+    String paramsValuesMessage = "";
+    if (correlationId != null) {
+      paramsValuesMessage = String.format("correlationId: %s", correlationId);
+    } else if (suiteName != null) {
+      paramsValuesMessage = String.format("suite name: %s", suiteName);
+      if (suiteVersion != null) {
+        paramsValuesMessage = String.format("%s, version: %s", paramsValuesMessage, suiteVersion);
+      }
+    }
+    response.getWriter()
+        .write(responseAsJson(GSON, "Unable to get Suite Metadata with %s for %s", paramsValuesMessage, dbKey.toString()));
+  }
+
   @Activate
   public void start() {
     register(Helper.getMetadataPath());