diff --git a/src/applications/harbormaster/editor/HarbormasterBuildTransactionEditor.php b/src/applications/harbormaster/editor/HarbormasterBuildTransactionEditor.php
--- a/src/applications/harbormaster/editor/HarbormasterBuildTransactionEditor.php
+++ b/src/applications/harbormaster/editor/HarbormasterBuildTransactionEditor.php
@@ -93,20 +93,37 @@
       return;
     }
 
-    id(new HarbormasterBuildCommand())
+    // establish separate connection to avoid HarbormasterBuildCommand
+    // being created in transaction which already is happening, otherwise
+    // Worker can be started before HarbormasterBuildCommand is committed
+    $conn = id(new HarbormasterBuildCommand())
+      ->establishConnection('w', $force_new = true);
+
+    $build_command = id(new HarbormasterBuildCommand())
+      ->setForcedConnection($conn)
       ->setAuthorPHID($xaction->getAuthorPHID())
       ->setTargetPHID($build->getPHID())
       ->setCommand($command)
       ->save();
 
-    PhabricatorWorker::scheduleTask(
-      'HarbormasterBuildWorker',
-      array(
-        'buildID' => $build->getID(),
-      ),
-      array(
-        'objectPHID' => $build->getPHID(),
-      ));
+    try {
+      PhabricatorWorker::scheduleTask(
+        'HarbormasterBuildWorker',
+        array(
+          'buildID' => $build->getID(),
+        ),
+        array(
+          'objectPHID' => $build->getPHID(),
+        ));
+    } catch (Exception $e) {
+      // if we can't schedule task, let's delete command
+      $build_command->delete();
+      throw $e;
+    } catch (Throwable $e) {
+      // if we can't schedule task, let's delete command
+      $build_command->delete();
+      throw $e;
+    }
   }
 
   protected function applyCustomExternalTransaction(