Missing Multiplayer Game

Hey guys,

today i wanted to boot up my multiplayergame with my friends, but stardew doesnt find the host game.
I looked in the AppData Stardew Folder but the files are missing for this save.
Somehow my buddy (which i got familyshare with) got the file instead of me.( It is the last save game before we ended, so its and old one but this is fine. Better redo 10 days instead of 3 seasons.) He can start it and he is playing with my character. When he invites me it forces me too create a new farmer.
I tried to copy that save in my folder but i cant boot it up
You guys have any ideas?