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

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。

备注：笔者所用手机是华为荣耀7，百度发现有人用小米手机也遇到这样的问题，解决方式是通用的，如果其他手机也遇到这种问题，欢迎大家留言讨论。

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。

到此问题已经解决。

如果你还没有解决，我也没有第三招了，如果你有了第三招，请记得留言告诉我一下~~~