In the Wacom Control Panel I assign "Eraser" to the lower sideswitch on my Wacom Intuos pen. It allows me to use the eraser function without flipping the pen, by pressing and holding the sideswitch while continuing to press and move the pen tip over the surface of the tablet. Unfortunately, it does not work in Krita. When I press and hold the sideswitch, the brush mode changes visibly from "Normal" to "Erase" in the brush tool panel, but the brush tip cursor disappears and nothing happens when I try to erase with the pen tip.

It's a real deal breaker in my workflow and the only reason I haven't switched from Photoshop to this great software yet. I would be immensely grateful if this problem could get fixed or if someone at least offered me a workaround.

Have you tried making a profile for krita and assinging keypress 'e' to that button? Or is that what you did and what is broken?

There are a couple of possible work-arounds that you could try.

If you map the pen switch to the keystroke "E".
This would toggle the current brush to eraser mode. Press again to return to paint mode. I find this more useful with a paint brush preset than with a pencil preset.

If you map the switch to "/", it will toggle between the last two brush presets. For example, I select an eraser preset, then immediately select the desired brush. Then as I work, I use the button (in my case on the tablet) that I have mapped to "/" to toggle between paint brush and eraser. This gives me a workflow that reminds me of working in Photoshop. If I select a third brush, though, I have to re-select the eraser and my favorite brush to get it back the way it was.

First of all, thank you guys for the quick responses!

@boudewijn: Assigning 'e' to the sideswitch works, but it's not the functionality I'm after.
@tparrott: That's ALMOST what I meant, yet not quite...

I guess what I'm really after is the ability to toggle between two brush presets temporarily by holding another key (similar to the way the ALT key in Photoshop works for the Color Picker). Basically:

1. Draw with the pen tip using Brush 1.
2. Keep drawing and press AND HOLD <another_key> to start using Brush 2.
3. Keep drawing and RELEASE <another_key> to go back to Brush 1.

Is/will something like this be possible? Thanks again for your help so far.

No... It's not possible atm to switch brushes in the middle of a stroke. I haven't got any plans to implement that, though I know it's possible in mypaint.

Hmm, I see. Well, it's not really necessary.

I would still consider the fact that after assigning the eraser to a sideswitch on my pen in the Wacom Control Panel and activating it in Krita, the brush mode changes to "Erase" but the cursor disappears and nothing else happens (no erasing possible)... It works as expected in virtually every other program I tried over the years (PS, Artrage, Sketchbook, MyPaint, Gimp, Manga Studio, SAI... just from the top of my head) . Do you have any plans to look into this issue?

I'd like to bump this issue because it happens to me too (and maybe for more people too)

I currently have a wacom bamboo tablet, and my stylus came without eraser tip, I've done the same as ogotay, I've set up a button for holding to erase, and it is frustrating that something as simple as erasing does not work at all, is even more issue for people without eraser in their stylus. This made me leave krita when I first tried it like 2 months ago

Maybe pressing E is the suggested workaround, but it also has a little problem... as a colemak keyboard user, the E key is too far to the right to be comfortable using it, it is placed where the K is in a normal keyboard... and it makes it even harder that we don't get the visual feedback from the keyboard, so it is harder because we have to learn it by heart and sometimes it takes some guesswork

I think this is an issue that should be looked for, as there is a lot of people with wacom tablets without erasers, and as ogotay said, it works with every other program out there, so if it doesn't work with krita is certainly a bug of krita.

At first I thought it was something misconfigured, until I searched further and found this thread. Maybe if the bug is not getting corrected soon, at least a message with the suggested workaround would be good for newcomers