When a Mule application fails to deploy, the mule_ee.log should capture the following event.
++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++ + Failed to deploy artifact + + 'yourApp', see below + ++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++
Below the "failed deploy" event should be the reason that the deploy failed. In this example, the reason the deploy failed was because the app expects a certain file (foo.xml) but the file cannot be found.
org.mule.module.launcher.InstallException: Config for app 'yourApp' not found: foo.xml