What the module of your phone?
Do you use the original charger + cable ?

Model: Samsung Galaxy Note8 N950F/DS

I am using an original power socket, but not the original cable.

I went to the Samsung store and they said "Its probably the cable or a software issue and your phone will need to be reset to have it fixed"

I'd try a different cable before going into reset the phone and loss all the data.
most of the charging problems occurs due to bad cables so first thing is to always change that and then Charger and then the Charging Sockets / Battery .

Displaced battery / Bent connectors / Busted battery / Liquid damage
These are the main reasons for that error, do not reset the phone have it repaired unless you can afford to lose data and still get it repaired.

/edit
use a pin and clean out the port, about the only thing "you" can do yourself without proper tools.

This post was edited by King Atrhur on Jul 1 2019 09:06am