annoted_source_code may return nil if an error happens during template compiling.

1 files changed, 1 insertions, 1 deletions

diff --git a/actionpack/lib/action_dispatch/middleware/show_exceptions.rb b/actionpack/lib/action_dispatch/middleware/show_exceptions.rb
index a7d3cb473f..ef0c9c51f5 100644
--- a/actionpack/lib/action_dispatch/middleware/show_exceptions.rb
+++ b/actionpack/lib/action_dispatch/middleware/show_exceptions.rb
@@ -127,7 +127,7 @@ module ActionDispatch
 
         ActiveSupport::Deprecation.silence do
           message = "\n#{exception.class} (#{exception.message}):\n"
-          message << exception.annoted_source_code if exception.respond_to?(:annoted_source_code)
+          message << exception.annoted_source_code.to_s if exception.respond_to?(:annoted_source_code)
           message << "  " << application_trace(exception).join("\n  ")
           logger.fatal("#{message}\n\n")
         end