Safety harness

src/Zope2/App/startup.py

@@ -209,7 +209,7 @@ class ZPublisherExceptionHook:
             # Zope 3 uses as well.
             view = queryMultiAdapter((v, REQUEST), name=u'index.html')
             if view is not None:
-                if IAcquirer.providedBy(published):
+                if IAcquirer.providedBy(view) and IAcquirer.providedBy(published):
                     view = view.__of__(published)
                 v = view()
                 response = REQUEST.RESPONSE