diff --git a/src/applications/maniphest/controller/ManiphestReportController.php b/src/applications/maniphest/controller/ManiphestReportController.php
--- a/src/applications/maniphest/controller/ManiphestReportController.php
+++ b/src/applications/maniphest/controller/ManiphestReportController.php
@@ -186,7 +186,11 @@
       switch ($row['transactionType']) {
         case ManiphestTaskStatusTransaction::TRANSACTIONTYPE:
           // NOTE: Hack to avoid json_decode().
-          $oldv = trim($row['oldValue'], '"');
+          if ($row['oldValue'] !== null) {
+            $oldv = trim($row['oldValue'], '"');
+          } else {
+            $oldv = null;
+          }
           $newv = trim($row['newValue'], '"');
           break;
         case ManiphestTaskMergedIntoTransaction::TRANSACTIONTYPE: