Eraser not working but it's not the "empty clipboard brush"-problem

[qsu]

Hi, I was successfully using the eraser tool to softly erase various layer's contents for about an hour. Then something happened and the eraser tool stopped doing anything now on my current project image.

What I've tried:

1. (dead end?) this Gimp-Forum thread and this official documentation both suggest I might be stuck on the "Clipboard" brush, with no clipboard contents.
   I've checked this and am quite sure I'm not on that brush. To be double sure I've explicitly picked a bunch of different brushes back and forth ("clipboard", "basic", "basic, sketch", etc) and toggling into and out of these brushes,.... none of these selections causes a change in "does nothing"-behavior
   
2. (dead end?) saved my work, and closed/re-opened gimp: same behavior.
   
3. (lead?) started a new gimp canvas with two layers: background color, and a transparent layer atop that with lots of dark pencil lines on top. voila I can erase pencil marks again! I have no idea what's different about my other XCF file that's causing it problems though...
   
4. (lead?) found a web result about "alpha layer" being on, but toggling this didn't change anything. or maybe I don't understand what an alpha layer is and how it relates...
   

Any ideas what setting/problem I might be having in my current project file? #3 and #4 might be leads, but I just don't know enough right now to know what to try next.

---

I'm on GIMP 2.10.38

---

I should clarify that I'm also certain that I've selected the layer I'm expecting an action on. The layer I have selected, if made visible/invisible (eye-icon) then indeed the content I'm trying to modify is the content that flashes on the screen.

---

another update: lead #4: I double-checked what alpha channel does for eraser tool (in my test file) and proved to myself that I undersatnd how alpha channel vs. background-selection impacts eraser tool. I'm still unable to cause anything to happen on my main file though.

interestingly: my main file is having this problem on any layer I try to erase on, not just one. So it's probably(?) not just a matter of some weird alpha channel setting on single layer.

---

ah I think I solved it! but the solution doesn't make any sense.

I tried to reproduce the "clipboard" problem by cutting something out of a layer, watching it appear among the brushes, then selecting one of the normal brushes just like I had before, and now my eraser works. But per my "thing I tried #1" I was already on a normal brush....

So I have NO idea what happened. Bug maybe? Anyway, just ... glad I solved it. I hope this helps someone else!!

[Ofnuts]

Good.

Another laundry list if nothing works: https://www.gimp-forum.net/Thread-When-s...ks-anymore

The best way to get a meaningful answer is to attach a screenshot of your entire Gimp UI (because if you haven't found out by yourself, you are probably looking at the wrong place, so showing us only where you think the problem is hides the right clues from us), with, in particular, the Tool options and Layers lists showing.

[PixLab]

(07-08-2024, 09:45 AM)Ofnuts Wrote: Good.

Another laundry list if nothing works: https://www.gimp-forum.net/Thread-When-s...ks-anymore

The best way to get a meaningful answer is to attach a screenshot of your entire Gimp UI (because if you haven't found out by yourself, you are probably looking at the wrong place, so showing us only where you think the problem is hides the right clues from us), with, in particular, the Tool options and Layers lists showing.

To add to the Ofnuts' link https://www.gimp-forum.net/Thread-Can-t-...n-that-one

[qsu]

(07-08-2024, 09:45 AM)Ofnuts Wrote: Another laundry list if nothing works: https://www.gimp-forum.net/Thread-When-s...ks-anymore

Oh wow, thanks! This would've been much more handy than that official docs link I'd found in all my web searches. Thanks! Hopefully this can get promoted a little higher.

(07-08-2024, 09:45 AM)Ofnuts Wrote: The best way to get a meaningful answer is to attach a screenshot of your entire Gimp UI (because if you haven't found out by yourself, you are probably looking at the wrong place, so showing us only where you think the problem is hides the right clues from us), with, in particular, the Tool options and Layers lists showing.

Noted for the future, will do! FWIW though, I did actually see those tips before I posted, but I thought it would be meaningless because I'd have to blur out all my actual art/visuals (so I figured there'd be zero clarity on which layers are involved and where the problem is). Anyway, I'll do it next time, even if that means censoring. Better than nothing I guess?

[Ofnuts]

(07-17-2024, 03:51 PM)qsu Wrote: Noted for the future, will do! FWIW though, I did actually see those tips before I posted, but I thought it would be meaningless because I'd have to blur out all my actual art/visuals (so I figured there'd be zero clarity on which layers are involved and where the problem is). Anyway, I'll do it next time, even if that means censoring. Better than nothing I guess?

You can also try to reproduce the problem on another picture made up for that purpose. If you can then you have something to show us, and if you can't then you may wonder what are the differences with your other picture and this can give you clues about what went wrong.