I got the same error when I upgraded my own instance. My quick workaround was to disable Plugins on my Mattermost system (go to System Console > Plugins (Beta) > Configuration).
@semin-lev If you are not using Plugin on your server, I suggest you to disable it. This is not satisfactory workaround but since Plugins are a beta feature, I didn’t investigate more for now.
I just opened an issue on our Github to made Plugins works, but considering the error log (a folder didn’t exists), I think people using Mattermost without Docker should have the problem too.