diff --git a/Library/Homebrew/cmd/update-report.rb b/Library/Homebrew/cmd/update-report.rb
index 4de380a772ec9a1f4e0ffa358aad77489777ccfc..7d17056b2696d20879521225eb89ae00ce1b57eb 100644
--- a/Library/Homebrew/cmd/update-report.rb
+++ b/Library/Homebrew/cmd/update-report.rb
@@ -149,7 +149,13 @@ module Homebrew
     else
       ohai "Deleting #{legacy_cache}..."
       FileUtils.rm_rf legacy_cache
-      FileUtils.touch migration_attempted_file if legacy_cache.exist?
+      if legacy_cache.exist?
+        FileUtils.touch migration_attempted_file
+        opoo <<-EOS.undent
+          Failed to delete #{legacy_cache}.
+          Please do so manually.
+        EOS
+      end
     end
   end
 end