diff --git a/src/applications/diffusion/controller/DiffusionRepositoryController.php b/src/applications/diffusion/controller/DiffusionRepositoryController.php
--- a/src/applications/diffusion/controller/DiffusionRepositoryController.php
+++ b/src/applications/diffusion/controller/DiffusionRepositoryController.php
@@ -40,6 +40,9 @@
     // If this VCS supports branches, check that the selected branch actually
     // exists.
     if ($drequest->supportsBranches()) {
+      $branch = $drequest->getBranch();
+      $tracking = $repository->shouldTrackBranch($branch);
+
       // NOTE: Mercurial may have multiple branch heads with the same name.
       $ref_cursors = id(new PhabricatorRepositoryRefCursorQuery())
         ->setViewer($viewer)
@@ -47,7 +50,7 @@
         ->withRefTypes(array(PhabricatorRepositoryRefCursor::TYPE_BRANCH))
         ->withRefNames(array($drequest->getBranch()))
         ->execute();
-      if ($ref_cursors) {
+      if ($ref_cursors && $tracking) {
         // This is a valid branch, so we necessarily have some content.
         $page_has_content = true;
       } else {
@@ -57,6 +60,17 @@
           $empty_message = pht(
             'There is no branch named "%s" in this repository.',
             $drequest->getBranch());
+        } else if (!$tracking) {
+          $empty_title = pht('Branch Not Tracked');
+          if ($default != $drequest->getBranch()) {
+            $empty_message = pht(
+              'The branch named "%s" is not being tracked.',
+              $drequest->getBranch());
+          } else {
+            $empty_message = pht(
+              'The branch named "%s" is configured as the default, but is not '.
+              'being tracked.', $drequest->getBranch());
+          }
         } else {
           $empty_title = pht('No Default Branch');
           $empty_message = pht(