You can configure how much information is being logged to the site's Event Viewer by configuring the log level under Configuration > General. Currently, you can choose between errors only or include debug messages.
The debug log level is useful for displaying actual XSL transform input, response data from shipping providers and payment gateways.
The debug log level writes a lot of data including all errors to the Event Viewer and may have an impact on performance. It is recommended to use error log level when in production.
To enable debugging, you must first make sure your Event Viewer is able to capture debug logs by following the steps below:
Under your site's Manage > Admin Logs, go to the Log Settings.
If you don't see "Debug Info" active in the list, click on Add Log Setting.
Tick the Logging checkbox and choose Log Type = "Debug Info". Click Save.
Now, you need to tell the Storefront to start logging in debug more
Under your Storefront administration Configuration > General settings, select Log Level = "Debug".