diff --git a/src/aphront/configuration/AphrontDefaultApplicationConfiguration.php b/src/aphront/configuration/AphrontDefaultApplicationConfiguration.php
index 9e5a8a6d05..7126f63995 100644
--- a/src/aphront/configuration/AphrontDefaultApplicationConfiguration.php
+++ b/src/aphront/configuration/AphrontDefaultApplicationConfiguration.php
@@ -88,15 +88,24 @@ class AphrontDefaultApplicationConfiguration
     $parser = new PhutilQueryStringParser();
     $data   = array();
 
+    // If the request has "multipart/form-data" content, we can't use
+    // PhutilQueryStringParser to parse it, and the raw data supposedly is not
+    // available anyway (according to the PHP documentation, "php://input" is
+    // not available for "multipart/form-data" requests). However, it is
+    // available at least some of the time (see T3673), so double check that
+    // we aren't trying to parse data we won't be able to parse correctly by
+    // examining the Content-Type header.
+    $content_type = idx($_SERVER, 'CONTENT_TYPE');
+    $is_form_data = preg_match('@^multipart/form-data@i', $content_type);
+
     $raw_input = PhabricatorStartup::getRawInput();
-    if (strlen($raw_input)) {
+    if (strlen($raw_input) && !$is_form_data) {
       $data += $parser->parseQueryString($raw_input);
     } else if ($_POST) {
       $data += $_POST;
     }
 
-    $data += $parser->parseQueryString(
-      isset($_SERVER['QUERY_STRING']) ? $_SERVER['QUERY_STRING'] : "");
+    $data += $parser->parseQueryString(idx($_SERVER, 'QUERY_STRING', ''));
 
     $request = new AphrontRequest($this->getHost(), $this->getPath());
     $request->setRequestData($data);