Good day
Initially game was working just fine but I changed one settings in game (set it not to change resolution), and, after that, game won't launch at all (please see screenshot attached).
Deleting Avernum4Settings.dat file didn't help and I didn't find any Spiderweb or Avernum related file in AppData folder or anywhere else.
Could you please help to revert what I did?
Thanks in advance

Support helped me and here I share my knowledge with you

In case you have the same error uninstall game completely and then install to different folder, say
C:\GOG Games\Avernum 4_1
instead of
C:\GOG Games\Avernum 4
and game will work like a charm again

Hope it would help someone