Building APK Failed

So while I was working on this project the last couple of times it worked properly, now since a few hours ago I’ve been getting errors while building an APK for Android. Here’s the relevant build log: MainFrameActions: Packaging (Android (ETC2)): CommandUtils.Run: Run: Took 2.6545 - Pastebin.com

And a mirror onto here of the most relevant portion:

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MainFrameActions: Packaging (Android (ETC2)): UEDeployAndroid.RunCommandLineProgramAndThrowOnError: Preparing native code for debugging...
MainFrameActions: Packaging (Android (ETC2)): UEDeployAndroid.MakeApk:
MainFrameActions: Packaging (Android (ETC2)): ====17/2/2015 5:55:41 PM====PERFORMING FINAL APK PACKAGE OPERATION================================================
MainFrameActions: Packaging (Android (ETC2)): UEDeployAndroid.RunCommandLineProgramAndThrowOnError: Making .apk with Ant... (note: it's safe to ignore javac obsolete warnings)
MainFrameActions: Packaging (Android (ETC2)):     [javac] Note: D:\Mantri\Explorer\Intermediate\Android\APK\src\com\android\vending\licensing\LicenseChecker.java uses or overrides a deprecated API.
MainFrameActions: Packaging (Android (ETC2)):     [javac] Note: Recompile with -Xlint:deprecation for details.
MainFrameActions: Packaging (Android (ETC2)): BUILD FAILED
MainFrameActions: Packaging (Android (ETC2)): D:\NVPACK_Full\android-sdk-windows\tools\ant\build.xml:892: The following error occurred while executing this line:
MainFrameActions: Packaging (Android (ETC2)): D:\NVPACK_Full\android-sdk-windows\tools\ant\build.xml:894: The following error occurred while executing this line:
MainFrameActions: Packaging (Android (ETC2)): D:\NVPACK_Full\android-sdk-windows\tools\ant\build.xml:906: The following error occurred while executing this line:
MainFrameActions: Packaging (Android (ETC2)): D:\NVPACK_Full\android-sdk-windows\tools\ant\build.xml:283: null returned: 1
MainFrameActions: Packaging (Android (ETC2)): Total time: 5 seconds
MainFrameActions: Packaging (Android (ETC2)): BuildCommand.Execute: ERROR: BUILD FAILED
MainFrameActions: Packaging (Android (ETC2)): Program.Main: ERROR: AutomationTool terminated with exception:
MainFrameActions: Packaging (Android (ETC2)): Program.Main: ERROR: Exception in UnrealBuildTool: ERROR: cmd.exe failed with args /c "D:\NVPACK_Full\apache-ant-1.8.2/bin/ant.bat" -quiet debug
MainFrameActions: Packaging (Android (ETC2)): Stacktrace:    at UnrealBuildTool.Android.UEDeployAndroid.RunCommandLineProgramAndThrowOnError(String WorkingD
MainFrameActions: Packaging (Android (ETC2)): irectory, String Command, String Params, String OverrideDesc, Boolean bUseShellExecute)
MainFrameActions: Packaging (Android (ETC2)):    at UnrealBuildTool.Android.UEDeployAndroid.MakeApk(String ProjectName, String ProjectDirectory, String OutputPath, String EngineDirectory, Boolean bForDistribution, String CookFlavor, Boolean bMakeSeparateApks, Boolean bIncrementalPackage)
MainFrameActions: Packaging (Android (ETC2)):    at UnrealBuildTool.Android.UEDeployAndroid.PrepForUATPackageOrDeploy(String ProjectName, String ProjectDirectory, String ExecutablePath, String EngineDirectory, Boolean bForDistribution, String CookFlavor)
MainFrameActions: Packaging (Android (ETC2)):    at AndroidPlatform.Package(ProjectParams Params, DeploymentContext SC, Int32 WorkingCL)
MainFrameActions: Packaging (Android (ETC2)):    at Project.Package(ProjectParams Params, Int32 WorkingCL)
MainFrameActions: Packaging (Android (ETC2)):    at BuildCookRun.DoBuildCookRun(ProjectParams Params)
MainFrameActions: Packaging (Android (ETC2)):    at BuildCommand.Execute()
MainFrameActions: Packaging (Android (ETC2)):    at AutomationTool.Automation.Execute(List`1 CommandsToExecute, CaselessDictionary`1 Commands)
MainFrameActions: Packaging (Android (ETC2)):    at AutomationTool.Automation.Process(String[] CommandLine)
MainFrameActions: Packaging (Android (ETC2)):    at AutomationTool.Program.MainProc(Object Param)
MainFrameActions: Packaging (Android (ETC2)):    at AutomationTool.InternalUtils.RunSingleInstance(MainProc Main, Object Param)
MainFrameActions: Packaging (Android (ETC2)):    at AutomationTool.Program.Main()
MainFrameActions: Packaging (Android (ETC2)): Program.Main: ERROR: ERROR: cmd.exe failed with args /c "D:\NVPACK_Full\apache-ant-1.8.2/bin/ant.bat" -quiet debug
MainFrameActions: Packaging (Android (ETC2)): ProcessManager.KillAll: Trying to kill 0 spawned processes.
MainFrameActions: Packaging (Android (ETC2)): Program.Main: AutomationTool exiting with ExitCode=1
MainFrameActions: Packaging (Android (ETC2)): Domain_ProcessExit
MainFrameActions: Packaging (Android (ETC2)): ProcessManager.KillAll: Trying to kill 0 spawned processes.
MainFrameActions: Packaging (Android (ETC2)): copying UAT log files...
MainFrameActions: Packaging (Android (ETC2)): RunUAT.bat ERROR: AutomationTool was unable to run successfully.
MainFrameActions: Packaging (Android (ETC2)): BUILD FAILED

While looking into it it seems to be an issue with ANT, not sure how to resolve this, or what causes it.

I made a thread on the forums and am updating it as I go along: