Created attachment 113916 [details] Stack trace I'm using Krita 4.2.0-prealpha (git commit 900c531) on MacOS Sierra 10.12.6. (Please note that I've enabled the new lock-free hash table.) File is E04P01.kra from David Revoy's Pepper&Carrot sources. Steps to follow: 1. Hide all layers except "ink" and "frame". 2. Select "frame", "Rasterize Layer", "Select Opaque", "Invert Selection". 3. Add a paint layer, hide "ink" and then paint the panels with white. Reorder layers to have "ink" on top of the new paint layer. 4. Finally, convert the image to Gray+Alpha, 8-bit. This triggers the following assertion: 2018-07-13 07:16:10.671605-0300 krita[16103:1680561] ASSERT (krita): "0 && "sanity check failed: the tile has already been removed!"" in file /Users/amalia/Desktop/krita/source/libs/image/tiles3/KisTiledExtentManager.cpp, line 53
I was able to reproduce this several times on Linux before it stopped working while testing if you have any unnecessary steps. I had the same assertion but didn't have enough time to do a stack trace. We also have amyspark on IRC who was able to reproduce it as well. Confirming this while I go back to testing.
I've managed to reproduce it again. Steps to follow: 1. Just convert image to Gray+Alpha, 8 bit. No need to hide or show any layers, it is only required to build Krita with the new lock-free hash table enabled. Video here (480p for ease of upload, but it's viewable enough): https://framadrop.org/r/jsjLUaCgbt#djiUsOVz+Os3UBIpsuxQuatA+bQKN7MQDO5Ru1OtjOQ= Please note I've printed the backtrace towards the end.