Hello, I've been building an app with log back-android and have it configured to use file and logcat appenders. It works exactly as I want when building a debug version via Eclipse ADT or with 'ant debug'. However, with a release build and Proguard enabled, I have ~50 warnings locating referenced classes from the javax.xml.Stream package. As far as I can tell, this package doesn't existin in android. Is there any additional dependency I have overlooked? I have downloaded both the slf4j and logback-android jar's and added the documented Proguard rules to my project as well. Below is a sample of my 'ant release' build log where project1 is my app and dependency is an android library project. [proguard] Reading input... [proguard] Reading program jar [/Users/chris/Projects/android/Android/project1/bin/proguard/original.jar] [proguard] Reading program jar [/Users/chris/Projects/android/Android/dependency/bin/classes.jar] [proguard] Reading program jar [/Users/chris/Projects/android/Android/Licensing/bin/classes.jar] [proguard] Reading program jar [/Users/chris/Projects/android/Android/dependency/libs/slf4j-api-1.7.6.jar] [proguard] Reading program jar [/Users/chris/Projects/android/Android/dependency/libs/logback-android-1.1.1-2.jar] [proguard] Reading program jar [/Users/chris/Projects/android/Android/project1/libs/android-support-v4.jar] [proguard] Reading library jar [/Users/chris/Projects/android/adt-bundle-mac-x86_64-20140624/sdk/platforms/android-19/android.jar] [proguard] Initializing... [proguard] Warning: ch.qos.logback.core.joran.event.stax.BodyEvent: can't find referenced class javax.xml.stream.Location [proguard] Warning: ch.qos.logback.core.joran.event.stax.BodyEvent: can't find referenced class javax.xml.stream.Location [proguard] Warning: ch.qos.logback.core.joran.event.stax.BodyEvent: can't find referenced class javax.xml.stream.Location [proguard] Warning: ch.qos.logback.core.joran.event.stax.BodyEvent: can't find referenced class javax.xml.stream.Location [proguard] Warning: ch.qos.logback.core.joran.event.stax.EndEvent: can't find referenced class javax.xml.stream.Location [proguard] Warning: ch.qos.logback.core.joran.event.stax.EndEvent: can't find referenced class javax.xml.stream.Location [proguard] Warning: ch.qos.logback.core.joran.event.stax.EndEvent: can't find referenced class javax.xml.stream.Location [proguard] Warning: ch.qos.logback.core.joran.event.stax.EndEvent: can't find referenced class javax.xml.stream.Location [proguard] Warning: ch.qos.logback.core.joran.event.stax.StartEvent: can't find referenced class javax.xml.stream.events.Attribute [proguard] Warning: ch.qos.logback.core.joran.event.stax.StartEvent: can't find referenced class javax.xml.stream.events.Attribute [proguard] Warning: ch.qos.logback.core.joran.event.stax.StartEvent: can't find referenced class javax.xml.stream.Location Thanks for the help, Chris