When friend tries to join the game or I try to join the game we get this error:

Cannot join. The following mod event handlers are not identical between you and the server. This indicates that the following mods are not multiplayer (save/load) safe. (See the log file for more details):

mod-atan-ash

More detailed:
33.032 Error ClientMultiplayerManager.cpp:1081: mod-atan-ash was registered for the following events when the map was saved but has not re-registered them as a result of loading: on_entity_died (ID 4)
33.032 Error ClientMultiplayerManager.cpp:86: MultiplayerManager failed: "" + multiplayer.script-event-mismatch + "
" + "
mod-atan-ash"
33.034 Info ClientMultiplayerManager.cpp:608: UpdateTick(3229) changing state from(ConnectedLoadingMap) to(Failed)
48.116 Info ClientMultiplayerManager.cpp:199: Quitting multiplayer connection.
48.116 Info ClientMultiplayerManager.cpp:608: UpdateTick(3229) changing state from(Failed) to(Disconnected)
48.116 Info ClientMultiplayerManager.cpp:217: Deleting active scenario (global = true).
48.184 Info UDPSocket.cpp:237: Closing socket
48.184 Info UDPSocket.cpp:267: Socket closed

I'm having the exact same issue

Need to register on_entity_died with events.on_load

"Sammie94
2 minutes ago

temp solution: save server, restart server, immediately pause server, let player join."

Need to register on_entity_died with events.on_load

Thanks. Added in 2.2.1.