diff --git a/model/dao/TaskDAO/PostgreSQLTaskDAO.php b/model/dao/TaskDAO/PostgreSQLTaskDAO.php
index 2771828e9..d25f3cf0d 100644
--- a/model/dao/TaskDAO/PostgreSQLTaskDAO.php
+++ b/model/dao/TaskDAO/PostgreSQLTaskDAO.php
@@ -707,13 +707,14 @@ public function partialUpdate(DirtyTaskVO $taskVO) {
             $resultMessage = "Task update failed:\n";
             if(strpos($errorMessage, "end_after_init_task")) {
                 $resultMessage .= "Start time later than end time.";
+                $result->setResponseCode(400);
             }
             else {
                 $resultMessage .= $errorMessage;
+                $result->setResponseCode(500);
             }
             $result->setMessage($resultMessage);
             $result->setIsSuccessful(false);
-            $result->setResponseCode(500);
         }
         else if (pg_affected_rows($res) == 1) {
             $result->setIsSuccessful(true);
@@ -742,7 +743,7 @@ public function batchPartialUpdate($tasks) {
             $result = new OperationResult(false);
             $result->setErrorNumber(10);
             $result->setMessage("Task update failed:\nDetected overlapping times.");
-            $result->setResponseCode(500);
+            $result->setResponseCode(400);
             return array($result);
         }
 
@@ -910,6 +911,7 @@ private function createInternal(TaskVO $taskVO) {
             $resultMessage = "Error creating task:\n";
             if(strpos($errorMessage, "end_after_init_task")) {
                 $resultMessage .= "Start time later than end time.";
+                $result->setResponseCode(400);
             }
             else if(strpos($errorMessage, "Not null violation")) {
                 $resultMessage .= "Missing compulsory data";
@@ -917,14 +919,15 @@ private function createInternal(TaskVO $taskVO) {
                     $resultMessage .= ": init and/or end time";
                 }
                 $resultMessage .= ".";
+                $result->setResponseCode(400);
             }
             else {
                 $resultMessage .= $errorMessage;
+                $result->setResponseCode(500);
             }
             $result->setErrorNumber($ex->getCode());
             $result->setMessage($resultMessage);
             $result->setIsSuccessful(false);
-            $result->setResponseCode(500);
         }
 
         return $result;
@@ -942,7 +945,7 @@ public function batchCreate($tasks) {
             $result = new OperationResult(false);
             $result->setErrorNumber(10);
             $result->setMessage("Task creation failed:\nDetected overlapping times.");
-            $result->setResponseCode(500);
+            $result->setResponseCode(400);
             return array($result);
         }
 
diff --git a/model/facade/action/CreateTasksAction.php b/model/facade/action/CreateTasksAction.php
index 5e8127945..dfbb2e63b 100644
--- a/model/facade/action/CreateTasksAction.php
+++ b/model/facade/action/CreateTasksAction.php
@@ -82,7 +82,7 @@ protected function doExecute() {
             if (!$configDao->isWriteAllowedForDate($task->getDate())) {
                 $result = new OperationResult(false);
                 $result->setErrorNumber(20);
-                $result->setResponseCode(500);
+                $result->setResponseCode(403);
                 $result->setMessage("Error creating task:\nNot allowed to write to date.");
                 $discardedResults[] = $result;
                 $discardedTasks[] = $task;
@@ -93,7 +93,7 @@ protected function doExecute() {
             if (!$projectVO || !$projectVO->getActivation()) {
                 $result = new OperationResult(false);
                 $result->setErrorNumber(30);
-                $result->setResponseCode(500);
+                $result->setResponseCode(403);
                 $result->setMessage("Error creating task:\nNot allowed to write to project.");
                 $discardedTasks[] = $task;
                 $discardedResults[] = $result;
diff --git a/model/facade/action/DeleteReportAction.php b/model/facade/action/DeleteReportAction.php
index 9d3038d7b..991fc99a2 100644
--- a/model/facade/action/DeleteReportAction.php
+++ b/model/facade/action/DeleteReportAction.php
@@ -77,7 +77,7 @@ protected function doExecute() {
         if(!$configDao->isWriteAllowedForDate($this->task->getDate())) {
             $result = new OperationResult(false);
             $result->setErrorNumber(20);
-            $result->setResponseCode(500);
+            $result->setResponseCode(403);
             $result->setMessage("Error deleting task:\nNot allowed to write to date.");
             return $result;
         }
@@ -87,7 +87,7 @@ protected function doExecute() {
         if (!$dao->checkTaskUserId($this->task->getId(), $this->task->getUserId())) {
             $result = new OperationResult(false);
             $result->setErrorNumber(50);
-            $result->setResponseCode(500);
+            $result->setResponseCode(403);
             $result->setMessage("Error deleting task:\nBelongs to a different user.");
             return $result;
         }
@@ -99,7 +99,7 @@ protected function doExecute() {
         if (!$projectVO || !$projectVO->getActivation()) {
             $result = new OperationResult(false);
             $result->setErrorNumber(30);
-            $result->setResponseCode(500);
+            $result->setResponseCode(403);
             $result->setMessage("Error updating task:\nNot allowed to write to project.");
             return $result;
         }
diff --git a/model/facade/action/PartialUpdateTasksAction.php b/model/facade/action/PartialUpdateTasksAction.php
index 47997be72..363170c07 100644
--- a/model/facade/action/PartialUpdateTasksAction.php
+++ b/model/facade/action/PartialUpdateTasksAction.php
@@ -88,7 +88,7 @@ protected function doExecute() {
                 if(!$configDao->isWriteAllowedForDate($task->getDate())) {
                     $result = new OperationResult(false);
                     $result->setErrorNumber(20);
-                    $result->setResponseCode(500);
+                    $result->setResponseCode(403);
                     $result->setMessage("Error updating task:\nNot allowed to write to date.");
                     $discardedResults[] = $result;
                     $discardedTasks[] = $task;
@@ -101,7 +101,7 @@ protected function doExecute() {
             if (!isset($oldTask)) {
                 $result = new OperationResult(false);
                 $result->setErrorNumber(40);
-                $result->setResponseCode(500);
+                $result->setResponseCode(400);
                 $result->setMessage("Error updating task:\nTask does not exist.");
                 $discardedResults[] = $result;
                 $discardedTasks[] = $task;
@@ -113,7 +113,7 @@ protected function doExecute() {
             if(!$configDao->isWriteAllowedForDate($oldTask->getDate())) {
                 $result = new OperationResult(false);
                 $result->setErrorNumber(20);
-                $result->setResponseCode(500);
+                $result->setResponseCode(403);
                 $result->setMessage("Error updating task:\nNot allowed to write to date.");
                 $discardedResults[] = $result;
                 $discardedTasks[] = $task;
@@ -126,7 +126,7 @@ protected function doExecute() {
                         $task->getId(), $task->getUserId())) {
                 $result = new OperationResult(false);
                 $result->setErrorNumber(50);
-                $result->setResponseCode(500);
+                $result->setResponseCode(403);
                 $result->setMessage("Error updating task:\nBelongs to a different user.");
                 $discardedResults[] = $result;
                 $discardedTasks[] = $task;
@@ -141,7 +141,7 @@ protected function doExecute() {
                 if (!$projectVO || !$projectVO->getActivation()) {
                     $result = new OperationResult(false);
                     $result->setErrorNumber(30);
-                    $result->setResponseCode(500);
+                    $result->setResponseCode(403);
                     $result->setMessage("Error updating task:\nNot allowed to write to project.");
                     $discardedResults[] = $result;
                     $discardedTasks[] = $task;
@@ -156,7 +156,7 @@ protected function doExecute() {
             if (!$projectVO || !$projectVO->getActivation()) {
                 $result = new OperationResult(false);
                 $result->setErrorNumber(30);
-                $result->setResponseCode(500);
+                $result->setResponseCode(403);
                 $result->setMessage("Error updating task:\nNot allowed to write to project.");
                 $discardedResults[] = $result;
                 $discardedTasks[] = $task;
diff --git a/web/services/createTasksService.php b/web/services/createTasksService.php
index 5fbdf950b..aa67d96a6 100644
--- a/web/services/createTasksService.php
+++ b/web/services/createTasksService.php
@@ -230,8 +230,8 @@
             return (!$item->getIsSuccessful());
         });
         if ($errors) {
-            //if multiple failures, let's just return a 500
-            http_response_code(500);
+            // if multiple failures, just return the code of the first one
+            http_response_code($errors[0]->getResponseCode());
             $string = "<return service='createTasks'><errors>";
             foreach((array) $errors as $result){
                 if (!$result->getIsSuccessful())
diff --git a/web/services/deleteTasksService.php b/web/services/deleteTasksService.php
index f131026c7..ddb04a835 100644
--- a/web/services/deleteTasksService.php
+++ b/web/services/deleteTasksService.php
@@ -131,8 +131,8 @@
             return (!$item->getIsSuccessful());
         });
         if ($errors) {
-            //if multiple failures, let's just return a 500
-            http_response_code(500);
+            // if multiple failures, just return the code of the first one
+            http_response_code($errors[0]->getResponseCode());
             $string = "<return service='deleteTasks'><errors>";
             foreach((array) $errors as $result){
                 if (!$result->getIsSuccessful())
diff --git a/web/services/updateTasksService.php b/web/services/updateTasksService.php
index 9ef770c49..315f61142 100644
--- a/web/services/updateTasksService.php
+++ b/web/services/updateTasksService.php
@@ -271,8 +271,8 @@
             return (!$item->getIsSuccessful());
         });
         if ($errors) {
-            //if multiple failures, let's just return a 500
-            http_response_code(500);
+            // if multiple failures, just return the code of the first one
+            http_response_code($errors[0]->getResponseCode());
             $string = "<return service='updateTasks'><errors>";
             foreach((array) $errors as $result){
                 if (!$result->getIsSuccessful())