When updating a multiplayer (2 players) save from 2.0, i got the error below.
The save had a decent amount of mods, can post them if needed. Could send the save itself too.
Crucially, Pelagos was removed while migrating as it's not yet on 2.1.
The mod Any Planet Start (1.2.6) caused a non-recoverable error.
Please report this error to the mod author.
Error while running event any-planet-start::on_player_changed_surface (ID 61)
any-planet-start/control.lua:125: attempt to index field 'character' (a nil value)
stack traceback:
any-planet-start/control.lua:125: in function 'respawn_player'
any-planet-start/control.lua:204: in function <any-planet-start/control.lua:200>