I had to debug an Android app running on an HUAWEI MediaPad M3. I connected it to my computer, started Android Studio and ran the app.
After a few minutes of working with the app I was wondering, why I could see all informational messages from the system and the app (calling Log.i), but no debug messages (Log.d) in the Android Studio Logcat window. I checked the developer options on the device and all Logcat settings in Android Studio, all to no result.
Still thinking I was missing some hidden Logcat setting I accidentally may have changed on my last debugging session, I searched the internet for help and found a surprising solution: Huawei devices preventing app debug messages by default! But there is a hidden settings menu, where you can change this default setting:
You have to start the calculator and enter the text „()()2846579()()“. This opens the hidden settings menu, where you have to open the „Background Settings“ –> „LOG settings“ menu and activate the „AP Log“ entry:
This setting will be reset after a restart of the device.
Please note, that for HUAWEI phones you have to dial a number instead („*#*#2846579#*#*“).
Also, depending on the Android version, the hidden settings menu and restart behavior may differ.