diff -u b/core/includes/common.inc b/core/includes/common.inc
--- b/core/includes/common.inc
+++ b/core/includes/common.inc
@@ -7345,6 +7345,10 @@
   registry_rebuild();
   system_rebuild_theme_data();
 
+  // Ensure that all modules that are currently supposed to be enabled are
+  // actually loaded.
+  module_load_all();
+
   // Update the list of bootstrap modules.
   // Allows developers to get new hook_boot() implementations registered without
   // having to write a hook_update_N() function.