If the Publishing Queue shows a status of Warning
The 'Warning' status means that the user configured a number of render errors to ignore, and one or more rendering errors occurred. If the setting was set correctly, this is not a problem.
When a user submits content for publishing (or unpublishing), the Advanced tab of the dialog includes a setting called Ignore Failures While Generating Publishable Content. If selected, the user can specify a number of allowed render failures, or no number (meaning infinite render failures are allowed).
If such failures subsequently occur, the status is set to 'Warning'. You can ignore this status if the user had a valid reason for selecting the setting and specifying the allowed number of failures.