[Android Central Question]

Whenever I lock my phone, 1 or 2 seconds after the screen going black, it is vibrating like I get a notification.
But I do not get one.
I have tried restarting the phone.

Device:
Galaxy A5 (2017)
Android 8.0.0

[belodion]

Was there a time when it didn't do it?

[Quini98]

It is pretty consistent.
And whenever it vibrates and I unlock with my finger it shows this. https://imgur.com/a/QDEWrJk
(Phone unlocked with fingerprint)
But normally it doesn't show that.

[belodion]

It sounds as if it's restarting then. I'm familiar with that phenomenon on the Lumia 1020 - fixed by switching off Bluetooth - but not on an Android phone. It may be a faulty Power switch. If it is that, it will need repair, but you could try flood-cleaning the button with alcohol.

It may also be worth trying Safe Mode.

I may also have misunderstood you: I assumed you meant powering off when you say lock. Am I wrong about that?

[Quini98]

I have tried restarting it and it doesn't fix it.
Bij locking I mean that I press the lock/power button so that my phone locks itself and the screen turns off.
When pressing the button again I have to give my code or fingerprint.

[belodion]

Ah, I see what you mean. I don't know why the vibration occurs. Adjusting the Lock Timer in Settings, Lock Screen - which is where it is on my phone at least - may be relevant.
The link in your post above does not work for me, incidentally, although I don't think it's necessary.