diff --git a/core/CronArchive.php b/core/CronArchive.php
index 4925d01c6568f6bbac1813b1357718d9cd57961a..5b3d53d7c1bd85054ccd951c84dc684bc1e723d8 100644
--- a/core/CronArchive.php
+++ b/core/CronArchive.php
@@ -1516,10 +1516,10 @@ class CronArchive
                 continue;
             }
 
-            $defaultReport = $userPreferences[APIUsersManager::PREFERENCE_DEFAULT_REPORT];
-            if (is_numeric($defaultReport)) {
+            if (isset($userPreferences[APIUsersManager::PREFERENCE_DEFAULT_REPORT])
+                && is_numeric($userPreferences[APIUsersManager::PREFERENCE_DEFAULT_REPORT])) {
                 // If user selected one particular website ID
-                $idSites = array($defaultReport);
+                $idSites = array($userPreferences[APIUsersManager::PREFERENCE_DEFAULT_REPORT]);
             } else {
                 // If user selected "All websites"  or some other random value, we pre-process all websites that he has access to
                 $idSites = APISitesManager::getInstance()->getSitesIdWithAtLeastViewAccess($userLogin);