diff --git a/packages/ruby/server/lib/server/dir.rb b/packages/ruby/server/lib/server/dir.rb
index 4949b997e..d64ef48b6 100644
--- a/packages/ruby/server/lib/server/dir.rb
+++ b/packages/ruby/server/lib/server/dir.rb
@@ -20,6 +20,9 @@ class Server::Dir
   rescue Errno::ENOENT
     body = "The requested URL was not found"
     [404, {"content-length" => body.bytesize, "content-type" => "text/plain"}, [body]]
+  rescue => ex
+    body = "Internal server error (#{ex.class})"
+    [500, {"content-length" => body.bytesize, "content-type" => "text/plain"}, [body]]
   end
 
   private
diff --git a/packages/ruby/server/test/server_dir_test.rb b/packages/ruby/server/test/server_dir_test.rb
index bbf55bcc6..f09c79978 100644
--- a/packages/ruby/server/test/server_dir_test.rb
+++ b/packages/ruby/server/test/server_dir_test.rb
@@ -43,6 +43,17 @@ class ServerDirTest < Test::Unit::TestCase
                  last_response.content_length
   end
 
+  def test_internal_server_error
+    def app.read(path) raise RuntimeError, "test" end
+    get "/"
+    assert_equal 500, last_response.status
+    assert_equal "text/plain", last_response.content_type
+    assert_equal "Internal server error (RuntimeError)".bytesize,
+                 last_response.content_length
+    assert_equal "Internal server error (RuntimeError)",
+                 last_response.body
+  end
+
   def test_permission_denied
     File.chmod 0, "./test/webroot/permission_denied.html"
     get "/permission_denied.html"