Hi, @Mako_Matt!
If you happen to have time, could you please test this updated package?
krita-5.2.0-crash-in-undo-dk4.zip — Яндекс.Диск
I have added a few intrusive sanity checks, so there is more probability to crash and catch the problem now. As with the previous package, the speed should be exactly the same as in normal Krita, and in case of a crash I need the backtrace.
PS:
I do really hope we can manage to track this bug down by the end of the week, then we could release Krita 5.1 next week. This bug in the only release blocker now 