How to disable Peek / Heads Up notifications globally in Android Oreo? [duplicate]

Question

There are multiple ways to disable Peek/Heads Up notifications in previous versions of Android (e.g. these or these), but it seems that the changes introduced by Oreo (Android 8.X) prevents them all. Is it possible to disable Heads Up notifications globally, for all apps, in Oreo?

I mean without disabling all normal notifications, or other features, but just this one. Ideally with no root required, but root solutions are also ok.

Answer 1

It's possible to disable the heads-up notifications with adb, without root, using one of the two options below. Sadly, on some of the most recent LG or Samsung phones, this setting is saved only in RAM, hence it only works until the next reboot.

Preliminary steps (required for both options)

On your phone:

• Disable "Disable alerts during game" feature (see this issue for details)
• Under Android Settings/Developer Options, enable USB Debugging;
• Under Android Settings/Developer Options/Select USB Configuration, enable PTP (Picture Transfer Protocol);
• Plug your phone to your computer.

On your computer:

1. Install Android Debug Bridge (adb);
2. Install the Universal ADB Drivers;
3. Run adb devices;
4. Verify your phone is listed under List of devices attached

On your phone:

• press OK on Allow USB Debugging?

Option 1

On your computer:

• Run ./adb shell settings put global heads_up_notifications_enabled 0

Option 2

On your phone:

1. Install SystemUI Tuner
2. Follow the instructions and run the required adb commands
3. Edit Quick Settings:

4. Add the Heads-up Notifications Toggle to quick settings:

5. Tap on the toggle to disable the heads-up notifications:

As mentioned above, both options work only until the next reboot on some phones which save this settings in RAM, so option 2 is more convenient because it allows to easily re-disable the heads-up notifications after reboot using the quick settings toggle.

Android 9 and above

It is possible to disable them from:

• Settings > Custom restrictions > Don't pop notifications on screen (source)

If that still doesn't work try disabling and enabling:

• Apps & notifications > Special app access > Adaptive Notifications (source)

Samsung Galaxy S21

Unfortunately none of the options mentioned above work for this phone: if you know a way to disable them without root please add a comment to this answer or an answer to the original question.

  

Answer 2

A root option is available, using the "Nougat / Oreo Quick Settings" app. The app itself doesn't require root, but the Heads Up quick-setting does. It basically enables multiple new quick-setting tiles in the Quick Settings Menu. One of them is "Heads-Up" (in category System (secure)), which allows to enable or disable Heads Up notifications. It is pretty easy to use:

• Open the app, search for "Heads-Up", tap on it and enable it.
• Edit the Quick Settings Menu, search for the new tile "Heads-Up", and drag it to the top panel.
• The tile will currently show it's enabled (in white or, in my case, blue). If you cannot disable it, you should make sure the app is granted root permissions.
• I needed to enable the Setting Run in aggressive mode in the app settings in order for it to work. It seems it depends on the phone to need that setting or otherwise.

Once it is disabled, Heads Up notifications will be globally disabled. And you can at any time enable them at will using that Quick Setting. This was tested in a rooted Oneplus 5T (OOS 5.0.4, on Android 8.0.0).