Why does my Mac build to Android fail? "Unable to install apk!"

Working with a friend to build an application on her Mac. After several successful builds to the Android device, Unity has begun to fail to transfer the .apk to the tablet.

The pop-up error is “Unable to install apk!” “Installation failed. See the Console for details.”

In the console, I find the following error message:

UnityException: Unable to install APK!
Installation failed. See the Console for details.
UnityEditor.Android.PostProcessor.CancelPostProcess.AbortBuild (System.String title, System.String message, System.Exception ex)
UnityEditor.Android.PostProcessor.CancelPostProcess.AbortBuild (System.String title, System.String message)
UnityEditor.Android.PostProcessor.CancelPostProcess.AbortBuildPointToConsole (System.String title, System.String message)
UnityEditor.Android.PostProcessor.Tasks.PublishPackage.UploadAndStartPlayer (UnityEditor.Android.PostProcessor.PostProcessorContext context, Boolean retryUpload)
UnityEditor.Android.PostProcessor.Tasks.PublishPackage.Execute (UnityEditor.Android.PostProcessor.PostProcessorContext context)
UnityEditor.Android.PostProcessor.PostProcessRunner.RunAllTasks (UnityEditor.Android.PostProcessor.PostProcessorContext context)
UnityEditor.Android.PostProcessAndroidPlayer.PostProcess (BuildTarget target, System.String stagingAreaData, System.String stagingArea, System.String playerPackage, System.String installPath, System.String companyName, System.String productName, BuildOptions options, UnityEditor.RuntimeClassRegistry

Please note: The tablet and Unity were working fine before this issue cropped up, and neither the tablet nor Unity have been updated over the last few days.

Does anybody know how I can fix this? Thanks in advance,


ADDITIONALLY: Does anybody know how I can look at the tablet’s memory while it’s connected to the Mac (ie. with Finder)? I’d like to be able to manually remove and install .apks to the tablet.

Did you turn on the developer mode in your tablet? Have you receive a panel in your tablet asking if it should trust the computer? Do your need extra driver for your computer to connect it (i know some phone need driver for pc)?