During debugging, Servoy Developer logs the activities of the debug client in the following file:
../application_server/servoy_log.txt

An additional (external) console window providing more detailed information can be launched by Eclipse by adding '-consoleLog' to the top of the servoy.ini file (for Mac users, this file is exposed when you view the Servoy application package contents and browse to the MacOS folder.) This console is useful for getting additional feedback during debugging.