diff --git a/src/applications/transactions/storage/PhabricatorApplicationTransaction.php b/src/applications/transactions/storage/PhabricatorApplicationTransaction.php
--- a/src/applications/transactions/storage/PhabricatorApplicationTransaction.php
+++ b/src/applications/transactions/storage/PhabricatorApplicationTransaction.php
@@ -244,7 +244,12 @@
         ->setNewValue($new_value);
     }
 
-    $metadata = $this->getMetadataValue('remarkup.control', array());
+    $metadata = $this->getMetadataValue('remarkup.control');
+
+    if (!is_array($metadata)) {
+      $metadata = array();
+    }
+
     foreach ($changes as $change) {
       if (!$change->getMetadata()) {
         $change->setMetadata($metadata);
diff --git a/src/applications/transactions/view/PhabricatorApplicationTransactionCommentView.php b/src/applications/transactions/view/PhabricatorApplicationTransactionCommentView.php
--- a/src/applications/transactions/view/PhabricatorApplicationTransactionCommentView.php
+++ b/src/applications/transactions/view/PhabricatorApplicationTransactionCommentView.php
@@ -325,6 +325,10 @@
     }
 
     $remarkup_control->setValue($draft_comment);
+
+    if (!is_array($draft_metadata)) {
+      $draft_metadata = array();
+    }
     $remarkup_control->setRemarkupMetadata($draft_metadata);
 
     if (!$this->getObjectPHID()) {