[Solved] Android Studio 3.0 Error: Error: INSTALL_FAILED_TEST_ONLY

Reason: After Android Studio 3.0, when generating debug apk, the android:testOnly=”true” attribute is automatically added in the application tag of the apk’s manifest file. android:testOnly=” true” This tag was originally used for testing, so packages with this tag cannot be installed in general, and need to be installed in a special way (by adding the -t flag).


Method 1: Set: android.injected.testOnly=false in the global configuration gradle.properties file in the project

Method 2: Add -t property: adb install -t app-debug.apk


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