When “myapp.apk” is installed, the following error is obtained:

[INSTALL_FAILED_VERIFICATION_FAILURE]

You must allow unsigned applications. Installation is blocked by Android. Allow non market applications to be installed in settings.

You need to disable verification of APK during ADB installation. If the security settings are grayed out or do not work properly, try shelling the device and running at each API level (global, system, security) according to the settings in the settings database

$ adb shell settings put global verifier_verify_adb_installs 0

If you can really set it, it will prevent APK checking through ADB.

Sometimes you need to disable the package verifier and use:

$ adb shell settings put global package_verifier_enable 0

You can see here that these settings are in the global database:

http://androidxref.com/4.4.2_r2/xref/frameworks/base/core/java/android/provider/Settings.java#5015