The AC adapter is not compatible with this system.

[Sureian]

I have bought a spare charger but when  connected comes up with the following error message:

The AC adapter is not compatible with this system.

The replacement charger is also an original HP charger.

[WAWood]

@Sureian 

Two possibilities -- both of which I have encountered -- could be true.

First, if you bought this online, they could have sent you the wrong charger. I did this for an All-in-One, even being careful to verify the HP part number, and when I got it, the charging plug did not even fit the PC!  I checked the part number, and it was wrong.  When I complained, the seller said chargers were "all the same"!  

Second, the charger could be defective -- but we here have no way to check that.  If there is another laptop using the same model, you can try it on that, but I don't know what else you can do other than return it.

[Sureian]

Hi WAWood

Thank you for your suggestion.

I may not be as tech savvy. My laptop has a USB-C type charging port and the original one (HP brand) that comes with it has  power rating of 65W.

I first bought an aftermarket spare 65W laptop charger. When plugged in, it charges for about 5 seconds and then "The AC adapter is not compatible with this system." error message is displayed and it stops charging.

I went ahead and bought another one  (another popular laptop manufacturer brand) with the same USB-C type and power rating. Also came up with the same error message before it stopped charging

I have now bought a HP brand USB-C type 65W charger. It has the same issue.

The one I have now looks different from the original one.

The original on looks like the one in the following link:

https://www.hp.com/au-en/shop/hp-65w-usb-c-power-adapter-1he08aa.html?istCompanyId=f8ba79ad-74d6-409...

The one I have bought now looks like the on in the following link:

https://www.hp.com/au-en/shop/hp-65w-usb-c-slim-travel-power-adapter-3pn48aa.html?istCompanyId=f8ba7...

Just so that you know, my original one still works fine. Just that it is too bulky to be carried around. 

Hope it clarifies my position.

[Sureian · Accepted solution]

I have managed to fix the problem by updating BIOS