diff --git a/src/applications/repository/engine/PhabricatorRepositoryDiscoveryEngine.php b/src/applications/repository/engine/PhabricatorRepositoryDiscoveryEngine.php
--- a/src/applications/repository/engine/PhabricatorRepositoryDiscoveryEngine.php
+++ b/src/applications/repository/engine/PhabricatorRepositoryDiscoveryEngine.php
@@ -682,7 +682,6 @@
 
     $this->queueCommitImportTask(
       $repository,
-      $commit->getID(),
       $commit->getPHID(),
       $task_priority,
       $via = 'discovery');
diff --git a/src/applications/repository/engine/PhabricatorRepositoryEngine.php b/src/applications/repository/engine/PhabricatorRepositoryEngine.php
--- a/src/applications/repository/engine/PhabricatorRepositoryEngine.php
+++ b/src/applications/repository/engine/PhabricatorRepositoryEngine.php
@@ -85,10 +85,9 @@
 
   final protected function queueCommitImportTask(
     PhabricatorRepository $repository,
-    $commit_id,
     $commit_phid,
     $task_priority,
-    $via = null) {
+    $via) {
 
     $vcs = $repository->getVersionControlSystem();
     switch ($vcs) {
@@ -109,7 +108,7 @@
     }
 
     $data = array(
-      'commitID' => $commit_id,
+      'commitPHID' => $commit_phid,
     );
 
     if ($via !== null) {
diff --git a/src/applications/repository/engine/PhabricatorRepositoryRefEngine.php b/src/applications/repository/engine/PhabricatorRepositoryRefEngine.php
--- a/src/applications/repository/engine/PhabricatorRepositoryRefEngine.php
+++ b/src/applications/repository/engine/PhabricatorRepositoryRefEngine.php
@@ -597,7 +597,6 @@
 
         $this->queueCommitImportTask(
           $repository,
-          $row['id'],
           $row['phid'],
           $task_priority,
           $via = 'ref');
diff --git a/src/applications/repository/management/PhabricatorRepositoryManagementReparseWorkflow.php b/src/applications/repository/management/PhabricatorRepositoryManagementReparseWorkflow.php
--- a/src/applications/repository/management/PhabricatorRepositoryManagementReparseWorkflow.php
+++ b/src/applications/repository/management/PhabricatorRepositoryManagementReparseWorkflow.php
@@ -247,7 +247,7 @@
       // all the requested steps explicitly.
 
       $spec = array(
-        'commitID' => $commit->getID(),
+        'commitPHID' => $commit->getPHID(),
         'only' => !$importing,
         'via' => 'reparse',
       );
diff --git a/src/applications/repository/worker/PhabricatorRepositoryCommitParserWorker.php b/src/applications/repository/worker/PhabricatorRepositoryCommitParserWorker.php
--- a/src/applications/repository/worker/PhabricatorRepositoryCommitParserWorker.php
+++ b/src/applications/repository/worker/PhabricatorRepositoryCommitParserWorker.php
@@ -11,30 +11,51 @@
       return $this->commit;
     }
 
-    $commit_id = idx($this->getTaskData(), 'commitID');
-    if (!$commit_id) {
+    $viewer = $this->getViewer();
+    $task_data = $this->getTaskData();
+
+    $commit_query = id(new DiffusionCommitQuery())
+      ->setViewer($viewer);
+
+    $commit_phid = idx($task_data, 'commitPHID');
+
+    // TODO: See T13591. This supports execution of legacy tasks and can
+    // eventually be removed. Newer tasks use "commitPHID" instead of
+    // "commitID".
+    if (!$commit_phid) {
+      $commit_id = idx($task_data, 'commitID');
+      if ($commit_id) {
+        $legacy_commit = id(clone $commit_query)
+          ->withIDs(array($commit_id))
+          ->executeOne();
+        if ($legacy_commit) {
+          $commit_phid = $legacy_commit->getPHID();
+        }
+      }
+    }
+
+    if (!$commit_phid) {
       throw new PhabricatorWorkerPermanentFailureException(
-        pht('No "%s" in task data.', 'commitID'));
+        pht('Task data has no "commitPHID".'));
     }
 
-    $commit = id(new DiffusionCommitQuery())
-      ->setViewer(PhabricatorUser::getOmnipotentUser())
-      ->withIDs(array($commit_id))
+    $commit = id(clone $commit_query)
+      ->withPHIDs(array($commit_phid))
       ->executeOne();
     if (!$commit) {
       throw new PhabricatorWorkerPermanentFailureException(
-        pht('Commit "%s" does not exist.', $commit_id));
+        pht('Commit "%s" does not exist.', $commit_phid));
     }
 
     if ($commit->isUnreachable()) {
       throw new PhabricatorWorkerPermanentFailureException(
         pht(
-          'Commit "%s" (with internal ID "%s") is no longer reachable from '.
-          'any branch, tag, or ref in this repository, so it will not be '.
+          'Commit "%s" (with PHID "%s") is no longer reachable from any '.
+          'branch, tag, or ref in this repository, so it will not be '.
           'imported. This usually means that the branch the commit was on '.
           'was deleted or overwritten.',
           $commit->getMonogram(),
-          $commit_id));
+          $commit_phid));
     }
 
     $this->commit = $commit;
@@ -64,7 +85,7 @@
     $repository = $commit->getRepository();
 
     $data = array(
-      'commitID' => $commit->getID(),
+      'commitPHID' => $commit->getPHID(),
     );
 
     $task_data = $this->getTaskData();
@@ -144,7 +165,7 @@
 
     $commit = id(new DiffusionCommitQuery())
       ->setViewer($viewer)
-      ->withIDs(array(idx($this->getTaskData(), 'commitID')))
+      ->withPHIDs(array(idx($this->getTaskData(), 'commitPHID')))
       ->executeOne();
     if (!$commit) {
       return $suffix;