Installation failed with message...It is possible that this issue is resolved by uninstalling an exi

错误弹窗如图：

Installation failed with message Failed to finalize session: INSTALL_FAILED_TEST_ONLY:installPackageLI.

It is possible that this issue is resolved by uninstalling an existing version of the apk if it is present, and then re-installing.

WARNING: Uninstalling will remove the application data!

Do you want to uninstall the existing application?

解决方法：

1、打开菜单File——Settings——Build,Execution,Deployment——Instant Run

2、不选中Enable Instant Run to hot swap code/resource changes on deploy(default enabled)

3、依次点击Apply——OK，重新运行程序，大功告成。 

如果你没有成功，接下来使用第二招。

1、打开Edit Configurations...

2、在Install Flags中写上“-t”

3、依次点击Apply——OK，重新运行，大功告成。