[Android exception] android studio Error type 3

When debugging on a real machine, android studio will transmit data like a real machine and install an app with the project name app. After debugging, uninstall the app on the phone. Then compile and run again and get an error Error type 3. The reason is that it was not uninstalled cleanly when uninstalling, and the app still exists in the mobile phone 设置, 应用列表resulting in the app with the project name already existing when compiling and uploading data. There are two solutions:
1) Uninstall the app under the application list;
2) Modify the value in the build.gradle file applicationId.