diff --git a/django/core/management.py b/django/core/management.py
index 5dd18ddd46..a2bacdcc48 100644
--- a/django/core/management.py
+++ b/django/core/management.py
@@ -1003,7 +1003,10 @@ def _check_for_validation_errors(app=None):
     s = StringIO()
     num_errors = get_validation_errors(s, app)
     if num_errors:
-        sys.stderr.write(style.ERROR("Error: %s couldn't be installed, because there were errors in your model:\n" % app))
+        if app:
+            sys.stderr.write(style.ERROR("Error: %s couldn't be installed, because there were errors in your model:\n" % app))
+        else:
+            sys.stderr.write(style.ERROR("Error: Couldn't install apps, because there were errors in one or more models:\n"))
         s.seek(0)
         sys.stderr.write(s.read())
         sys.exit(1)