diff --git a/CHANGELOG.md b/CHANGELOG.md
index 1c664ab..7ba027f 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -9,6 +9,8 @@ and this project adheres to [Semantic Versioning](http://semver.org/).
 ## Added
 - Tags in ActionSchema
 - Entity name in ActionSchema
+## Changed
+- Removed empty elements from transport writes
 
 ## [1.2.8] - 2017-11-07
 ## Changed
diff --git a/src/Mapper/CompactTransportMapper.php b/src/Mapper/CompactTransportMapper.php
index 2c2db52..2f38392 100644
--- a/src/Mapper/CompactTransportMapper.php
+++ b/src/Mapper/CompactTransportMapper.php
@@ -88,13 +88,27 @@ public function writeTransport(Transport $transport)
     {
         $output = [];
         $output = $this->writeTransportMeta($transport->getMeta(), $output);
-        $output = $this->writeTransportFiles($transport->getFiles(), $output);
-        $output = $this->writeTransportData($transport->getData(), $output);
-        $output = $this->writeTransportRelations($transport->getRelations(), $output);
-        $output = $this->writeTransportLinks($transport->getLinks(), $output);
-        $output = $this->writeTransportCalls($transport->getCalls(), $output);
-        $output = $this->writeTransportTransactions($transport->getTransactions(), $output);
-        $output = $this->writeTransportErrors($transport->getErrors(), $output);
+        if ($transport->getFiles()->getAll()) {
+            $output = $this->writeTransportFiles($transport->getFiles(), $output);
+        }
+        if ($transport->getData()->get()) {
+            $output = $this->writeTransportData($transport->getData(), $output);
+        }
+        if ($transport->getRelations()->get()) {
+            $output = $this->writeTransportRelations($transport->getRelations(), $output);
+        }
+        if ($transport->getLinks()->get()) {
+            $output = $this->writeTransportLinks($transport->getLinks(), $output);
+        }
+        if ($transport->getCalls()->get()) {
+            $output = $this->writeTransportCalls($transport->getCalls(), $output);
+        }
+        if ($transport->getTransactions()->get()) {
+            $output = $this->writeTransportTransactions($transport->getTransactions(), $output);
+        }
+        if ($transport->getErrors()->get()) {
+            $output = $this->writeTransportErrors($transport->getErrors(), $output);
+        }
         if ($transport->hasBody()) {
             $output = $this->writeTransportBody($transport->getBody(), $output);
         }
@@ -459,9 +473,6 @@ public function writeTransportTransactions(TransportTransactions $transactions,
 
             if ($transaction->getParams()) {
                 $transactionData['p'] = array_map([$this, 'writeParam'], $transaction->getParams());
-            } else {
-                // todo: remove when katana makes parameters optional
-                $transactionData['p'] = [];
             }
 
             $type = [
@@ -517,11 +528,17 @@ public function getTransportErrors(array $raw)
     public function writeTransportErrors(TransportErrors $errors, array $output)
     {
         foreach ($errors->get() as $error) {
-            $output['e'][$error->getAddress()][$error->getService()][$error->getVersion()][] = [
-                'm' => $error->getMessage(),
-                'c' => $error->getCode(),
-                's' => $error->getStatus(),
-            ];
+            $errorData = [];
+            if ($error->getMessage()) {
+                $errorData['m'] = $error->getMessage();
+            }
+            if ($error->getCode()) {
+                $errorData['c'] = $error->getCode();
+            }
+            if ($error->getStatus()) {
+                $errorData['s'] = $error->getStatus();
+            }
+            $output['e'][$error->getAddress()][$error->getService()][$error->getVersion()][] = $errorData;
         }
 
         return $output;
diff --git a/src/Mapper/ExtendedTransportMapper.php b/src/Mapper/ExtendedTransportMapper.php
index d3e42e5..854b060 100644
--- a/src/Mapper/ExtendedTransportMapper.php
+++ b/src/Mapper/ExtendedTransportMapper.php
@@ -88,13 +88,28 @@ public function writeTransport(Transport $transport)
     {
         $output = [];
         $output = $this->writeTransportMeta($transport->getMeta(), $output);
-        $output = $this->writeTransportFiles($transport->getFiles(), $output);
-        $output = $this->writeTransportData($transport->getData(), $output);
-        $output = $this->writeTransportRelations($transport->getRelations(), $output);
-        $output = $this->writeTransportLinks($transport->getLinks(), $output);
-        $output = $this->writeTransportCalls($transport->getCalls(), $output);
-        $output = $this->writeTransportTransactions($transport->getTransactions(), $output);
-        $output = $this->writeTransportErrors($transport->getErrors(), $output);
+
+        if ($transport->getFiles()->getAll()) {
+            $output = $this->writeTransportFiles($transport->getFiles(), $output);
+        }
+        if ($transport->getData()->get()) {
+            $output = $this->writeTransportData($transport->getData(), $output);
+        }
+        if ($transport->getRelations()->get()) {
+            $output = $this->writeTransportRelations($transport->getRelations(), $output);
+        }
+        if ($transport->getLinks()->get()) {
+            $output = $this->writeTransportLinks($transport->getLinks(), $output);
+        }
+        if ($transport->getCalls()->get()) {
+            $output = $this->writeTransportCalls($transport->getCalls(), $output);
+        }
+        if ($transport->getTransactions()->get()) {
+            $output = $this->writeTransportTransactions($transport->getTransactions(), $output);
+        }
+        if ($transport->getErrors()->get()) {
+            $output = $this->writeTransportErrors($transport->getErrors(), $output);
+        }
         if ($transport->hasBody()) {
             $output = $this->writeTransportBody($transport->getBody(), $output);
         }
@@ -439,9 +454,6 @@ public function writeTransportTransactions(TransportTransactions $transactions,
 
             if ($transaction->getParams()) {
                 $transactionData['params'] = array_map([$this, 'writeParam'], $transaction->getParams());
-            } else {
-                // todo: remove when katana makes parameters optional
-                $transactionData['params'] = [];
             }
 
             $type = $transaction->getType();
@@ -490,11 +502,17 @@ public function getTransportErrors(array $raw)
     public function writeTransportErrors(TransportErrors $errors, array $output)
     {
         foreach ($errors->get() as $error) {
-            $output['errors'][$error->getService()][$error->getVersion()][] = [
-                'message' => $error->getMessage(),
-                'code' => $error->getCode(),
-                'status' => $error->getStatus(),
-            ];
+            $errorData = [];
+            if ($error->getMessage()) {
+                $errorData['message'] = $error->getMessage();
+            }
+            if ($error->getCode()) {
+                $errorData['code'] = $error->getCode();
+            }
+            if ($error->getStatus()) {
+                $errorData['status'] = $error->getStatus();
+            }
+            $output['errors'][$error->getService()][$error->getVersion()][] = $errorData;
         }
 
         return $output;