Example 1: Delete _all_ factory brushes, when there are no user defined brushes. Quit Krita. Start Krita. Krita will complain that there are no brush presets and quit. Example 2: Delete _nearly all_ factory brushes (leave on remaining in my case), and define a few user defined ones. Crashes occur often, for example after configuration changes, and most recently when saving a .kra file. Reproducible: Sometimes Steps to Reproduce: 1. Delete all factory presets, then restart krita. 2. Alternatively: Delete all factory presets except one, restart krita, create user presets, then delete the remaining factory preset and restart krita. 3. Actual Results: In case of 1. Krita complains that there are no factory brushes and aborts. In case of 2. Krita crashes often (sometimes while saving a .kra, with a segv, and with KisPaintOpPreset methods near the top of the stack trace, but not always; sometimes when changing configuration) Expected Results: Krita should work perfectly fine with all factory brushes deleted (or blacklisted). At present, 2.9.2 does not. Apologies for not fitting exactly into what the bug report asks for.
Created attachment 93557 [details] Crash log generated when reproducing this bug I deleted my config, did an apt-get remove and apt-get install of krita 2.9.2 on Ubuntu 15.04 prior to this. An attempted screen recording is at https://youtu.be/lZ3qmGl_T-0, and the crash log generated by this crash is attached. (The screen recording is far from ideal in quality, with various parts of windows not being captured -- that is an issue for the gtk-recordmydesktop people -- but I thought it worth recording an attaching in any case.)
Sorry that this is so late. 1. Is expected. Krita just doesn't have the flexibility to understand having no presets. For 2. The backtrace is quite strange. I am suspecting it is attempting to find non-existent factory presets that you deleted. Both are pretty awkward, but the latter needs some more diagnosis on our end. Thanks for reporting in the meantime!
Krita now handles the situation where there are no paintop presets left more gracefully. I'm setting this to fixed. Tested with git 4cac9dfe7039fb2bc39658025088947dbe3435b7