Device Owner Setup

Unfortunately the Android security model does not make it possible for one application to enable or disable components for another application. This makes sense for standard applications because you wouldn't want a competing application to be able to disable yours. That is why App Manager requires device owner privileges in order to achieve this.

It is possible to activate device owner on a device without a factory reset. That being said, if you are encountering errors with device owner activation then the simplest way to resolve them is to factory reset the device and activate device owner as soon as possible (i.e. right after adding a Google account to download the application from the Play Store).

Once you have activated device owner you will need to use the Uninstall option inside the application in order to remove device owner and uninstall the application.

adb: device unauthorized

The device is offline or hasn't authorized USB debugging. Reconnect it, accept the USB debugging prompt on the device (tick “Always allow from this computer”), and try again.

Error: Unknown admin: ComponentInfo{com.ccswe.appmanager.deviceowner/com.ccswe.appmanager.receivers.DeviceAdminReceiver}

App Manager isn't installed on the device. Install App Manager from Google Play, then try again.

Some devices (confirmed Samsung Galaxy S8) do not properly report an error when there are non-Google accounts on the device that are blocking activation. The helper waits up to a minute, then stops and tells you to remove more accounts; the raw ADB command can hang indefinitely. Either way, remove additional accounts — including manufacturer accounts — and try again.

java.lang.IllegalStateException: Not allowed to set the device owner because there are already several users on the device.

An application on your device, such as Samsung's Secure Folder, has already created additional user profiles. You will need to disable these applications prior to enabling device owner.

java.lang.IllegalStateException: Not allowed to set the device owner because there are already some accounts on the device.

There are still accounts that need to be removed from the device. If you have already removed all your Google accounts then check for device manufacturer accounts (e.g. Samsung) and temporarily remove those. Keep removing accounts until you are successful.

java.lang.IllegalStateException: Trying to set device owner but device is already provisioned.

Cannot set the device owner if the device is already set-up.

Newer Android phrases this differently, but the cause is the same — you still have one or more accounts on the device that you need to remove.

java.lang.IllegalStateException: Trying to set device owner but device owner is already set.

There is already an application with device owner on the device. If this application is not App Manager (Device Owner) then you will need to uninstall it before you can activate device owner.