This bug has been puzzling me because it only happens in a very specific condition, and it is a bit tricky to reproduce, and when it does happen, Krita crashes, and it doesn't create a crash log either. So I use a custom Filter Engine brush with the Color Adjustment filter to sometimes change the alpha value of my lineart when I ink. (The "alpha" channel in the filter settings has points on the graph.) For example, my settings are such that applying a brushstroke with this brush will decrease the alpha value. Another one of my custom brushes increases the alpha. What I've noticed is that whenever I select this brush from the Brush Presets list, there is a very small chance Krita will crash. It doesn't always happen. Sometimes I select the brush and I can use it normally. But on rare occasions when I do select it, it will eventually cause the Krita UI to freeze for a few seconds, and then the whole app will then crash. Another observation is that the crash never happens when selecting the default Filter brushes that come with Krita. In other words, the "Filter Blur" and "Filter Sharpen" brushes never crash when selecting it. This leads me to believe that only specific Filter Brushes with specific filters cause it. The quickest way to reproduce this crash is to open your Brush Preset list, and rapidly switch between the custom Filter Engine brush and the default Krita brushes repeatedly. And maybe make a few brush strokes on the canvas while you do this. It probably won't crash right away, but if you keep switching between your brushes and this Color Adjustment filter brush long enough, it will eventually trigger a crash, as though you finally encountered a shiny Pokemon, heh. I don't think this crash happens on the desktop version. I've only encountered it on Android, so I'm probably 90% sure it's Android exclusive. STEPS TO REPRODUCE 1. Create a new Filter Engine brush with the Color Adjustment filter. Put whatever setting in the filter's alpha channel. 2. Bring up your Brush Presets list by pressing the brush thumbnail on the toolbar ("Painter's Tools" action). 3. Choose your custom Filter Engine brush OBSERVED RESULT A very low chance that Krita will crash. Maybe 5% or 10% chance? You will probably need to select this brush many times for the crash to happen. You'll encounter the crash faster if you rapidly switch between this custom brush and other default brushes repeatedly, and maybe making a few brush strokes along the way. When the bug finally occurs, the UI will freeze for a few seconds upon selecting the Color Adjustment brush, and then crash to the Android home screen. EXPECTED RESULT Should never crash when selecting a brush. Note that the crash does NOT happen with default brush like Filter Blur and Filter Sharpen. SOFTWARE/OS VERSIONS Android 15 arm64 APK Krita 5.2.9 and the latest 5.3 nightly at the time of this post
Also, the crash can happen on a clean install. So all of Krita's settings are in the default mode other than making this Filter Engine brush with Color Adjustment filter.
Created attachment 180837 [details] Video of crash. Crash occurs at 2:12 Video of crash uploaded. Crash occurs at 2:12
Created attachment 180838 [details] Color adjustment filter brush that causes crash when selecting it Here is the color adjustment filter brush that causes the crash when selecting it. (See attachment)
I did some more testing, and I now found a way to reproduce the crash easily. 1. Do a clean install of https://download.kde.org/stable/krita/5.2.9/krita-arm64-v8a-5.2.9-release-signed.apk 2. Create a new image, and save it as a .kra file 3. Open the Brush Editor, and create and save a new Filter Engine brush with the following settings: Filter: Color Adjustment Channel: Alpha The two points on the graph should have the following settings: Point A: input 0, output 0 Point B: input 255, output 0 So the points should be at the bottom of the graph. 4. Select this new brush. 5. Close the document (should now appear as a thumbnail on "Recent Images") 6. Quit Krita, and restart the app 7. With your new brush now selected upon launch, do the following 5 times: Open the .kra file, either through clicking the thumbnail, or the "Open Image" button. Then close the .kra file. The fifth time you attempt to open the .kra file, Krita should crash. (Try a 6th or 7th time just in case it doesn't though.)
Update: I tried to reproduce this crash on ChromeOS, which is running a x86_64 build of the .APK according to the system information. The crash didn't happen there doing the steps in the previous post I WAS able to reproduce this crash multiple times successfully on my Android device with the steps in the previous post, though. This leads me to believe the crash only happens in the ARM version on Android.
A second user on krita-artists has confirmed the crash on their end: https://krita-artists.org/t/android-users-can-you-confirm-the-following-crash-happens-on-your-device/128729