Hi,
I'm using a Huion 610, and Windows 8.1.
My PC;
Model #: 23-g010
Product #: F3D37AAR#ABA
Software Build #: 14AM1ARA602#SABA#DABA
Service ID #: 20140721
PCBRAND #: HP
4GB ram, running at 1.3 GHz

I've been using Krita for a few years now with not much problem, until upgrading to Krita 4.2.1
Every time I click to open the pop-up pallet/brush selector, or click the undo button on my Huion, Krita crashes..
I tried going back to version 3.9 But it doesn't help. I just upgraded to V4.2.4. same thing happens. I tried uninstalling and reinstalling my tablet drivers.
I have a flash drive with Krita portable 3.0 that sorta works, but now I'm spoiled. I want my Krita back.

Thanks,
Jim

This sounds much more like a GPU driver issue than a tablet issue. Please check if this still happens if you switch GPU accceleration in Krita from OpenGL to Angle, and if it still occurs, if you switch off GPU acceleration altogether.