Hello again,
I don't know if there is a proper topic about it, please send me in if so.
The problem is that after patching game to 1.3 and the GECK as well (hmm... it is just a replacement file) I can't create working ESM file. ESP is working without issues however converting it to ESM makes "Fallout stops working and will be closed" error. I tried to convert with GECK (it was working before to rename file into ESM, load to GECK and save), with FoMM and with FNVEdit without success. Any tips please what's going on currently? Has anyone the problem as well?

In the 1.3 game patch, there are a small number of changed objects. It is possible that your mod changes one of these objects and may no longer work. Try creating a very simple new mod, for example by moving the gurney in Doc Mitchell's house. Can you convert this mod to esm? If yes, then the problem may be unique to your mod. If no, are you sure both geck and game are version 1.3?