https://pastebin.com/4JEYdwnf
I don't know why this is happening.

Very strange. Do you have "fake players" that actually show up in the player list?
Does it happen a lot?

This happened 1 time, is it possible to take into account create and its installation for a fake player?
I have 1 NPC which stands on spawn and opens the menu to players, but it's been there for over a week now

Fake players should be fine. It's just strange that it seems like there's supposedly an "actual" player that wasn't handled properly on log in. Can you check the log where this crash is from? Maybe there is an earlier error there.

@XionioXMaster Thanks. I think I was right. There is an earlier error unrelated to my mods. It happens while checking if the logged in player is banned. In your case it was the player "Pavel1l". It throws an error and skips the Forge event that handles logged in players.
If you have an idea what mod is affecting user bans, please let me know.

I don't know if this is related but it is certainly something.

Anyway, I'm sure the original report was the same exact issue, so I'm closing this.

You don't have to be banned for this to be related to player bans. It is related to player bans 100%. That's what the first error is that is thrown in the full log, which is the reason the Forge event isn't fired. Whatever it is, it is not to be fixed on my end. The event is obviously supposed to be fired.