CODE EXAMPLE FOR SHELL

java.util.concurrent.ExecutionException: com.android.builder.testing.api.DeviceException: com.android.ddmlib.InstallException: INSTALL_FAILED_VERSION_DOWNGRADE: Package Verification Result

You probably need to allocate more internal memory to your emulator. 
This can be done by:

1. Opening Android Virtual Device Manager...

2. Edit the device you are having a problem with.

3. Show Advanced Settings 

4. Increase the internal storage to 5120MB

5. Restart the emulator (cold boot)