ADB Install Fails With INSTALL_FAILED_TEST_ONLY

Question

Looks like you need to modify your AndroidManifest.xml
Change android:testOnly="true" to android:testOnly="false" or remove this attribute.

If you want to keep the attribute android:testOnly as true you can use pm install command with -t option, but you may need to push the apk to device first.

$ adb push bin/hello.apk /tmp/
5210 KB/s (825660 bytes in 0.154s)

$ adb shell pm install /tmp/hello.apk 
    pkg: /tmp/hello.apk
Failure [INSTALL_FAILED_TEST_ONLY]

$ adb shell pm install -t /tmp/hello.apk 
    pkg: /tmp/hello.apk
Success

I was able to reproduce the same issue and the above solved it.

If your APK is outside the device (on your desktop), then below command would do it:

$ adb install -t hello.apk

I had a similar problem with Android Studio 3.0.0 Beta 7 and could not publish anymore to the play store.

As stated here: https://developer.android.com/studio/run/index.html

Note: The Run button builds an APK with testOnly="true", which means the APK can only be installed via adb (which Android Studio uses). If you want a debuggable APK that people can install without adb, select your debug variant and click Build > Build APK(s).

Same goes for release build, with Android Studio 3 you need to go to Build > Build APK(s) to have a non testable release apk that you can submit to the store.

Add -t install flag, as on the screenshot below:

In my case this mistake was in unstable gradle version. Just use a stable version of gradle (not alpha, not even beta). And it was fixed for me

After searching and browsing all day, the only one works is adding

android.injected.testOnly=false

to the gradle.properties file

I agree with Elisey. I got this same error after opening my project in the 2.4 preview and then opening the same project in android studio 2.3

Fixed the issue by changing this line in build.gradle from

classpath 'com.android.tools.build:gradle:2.4.0-alpha5'

to

classpath 'com.android.tools.build:gradle:2.3.1'