Unable to convert classes to dex format - Android issue

I've been wracking my brain on this issue, never had it before. Tried so many different things. I am on a mac, attempting to deploy an Android version of our app. I keep getting this error:

Error building Player: CommandInvokationFailure: Unable to convert classes into dex format. See the Console for details.
/System/Library/Frameworks/JavaVM.framework/Versions/CurrentJDK/Home/bin/java -Xmx1024M...

Unable to convert classes to dex format - Android issue