So I’ve finally found the solution. The error from output log shows path to a files that names “Level3.umap” and “Level17.umap”. The problem is actually file “Level17.umap” has never existed. At least I’ve never created. I was wondering how is it possible to shows path to a file that doesn’t exist? So decided to just change the directory of all maps that i have in my game. And voila! All erros disappeared!