[ci skip] Upgrading assets.unknown_asset_fallback

1 files changed, 12 insertions, 0 deletions

diff --git a/guides/source/upgrading_ruby_on_rails.md b/guides/source/upgrading_ruby_on_rails.md
index 2372590cec..4530990280 100644
--- a/guides/source/upgrading_ruby_on_rails.md
+++ b/guides/source/upgrading_ruby_on_rails.md
@@ -1444,6 +1444,18 @@ config.public_file_server.headers = {
 }
 ```
 
+### config/initializers/assets.rb
+
+In the most recent verison of sprockets-rails there is a flag available to configure what happens when
+an asset lookup is performed and no asset is found. By setting this value to false, an error will be
+raised so the asset lookup does not fail silently.
+
+```ruby
+# Unknown asset fallback will return the path passed in when the given
+# asset is not present in the asset pipeline.
+Rails.application.config.assets.unknown_asset_fallback = false
+```
+
 ### config/initializers/wrap_parameters.rb
 
 Add this file with the following contents, if you wish to wrap parameters into a nested hash. This is on by default in new applications.