diff --git a/src/applications/auth/constants/PhabricatorCookies.php b/src/applications/auth/constants/PhabricatorCookies.php
--- a/src/applications/auth/constants/PhabricatorCookies.php
+++ b/src/applications/auth/constants/PhabricatorCookies.php
@@ -164,7 +164,7 @@
     // Old cookies look like: /uri
     // New cookies look like: timestamp,/uri
 
-    if (!strlen($cookie)) {
+    if (!phutil_nonempty_string($cookie)) {
       return null;
     }
 
diff --git a/src/applications/people/cache/PhabricatorUserProfileImageCacheType.php b/src/applications/people/cache/PhabricatorUserProfileImageCacheType.php
--- a/src/applications/people/cache/PhabricatorUserProfileImageCacheType.php
+++ b/src/applications/people/cache/PhabricatorUserProfileImageCacheType.php
@@ -91,6 +91,9 @@
   }
 
   public function isRawCacheDataValid(PhabricatorUser $user, $key, $data) {
+    if ($data === null) {
+      return false;
+    }
     $parts = explode(',', $data, 2);
     $version = reset($parts);
     return ($version === $this->getCacheVersion($user));