This notice popped up when finishing researching the Tank tech;

Error while running event level::on_tick (ID 0)
Map doesn't contain 1 player, this function can't be used
stack traceback:
[C]: in function 'show_message_dialog'
...Data/Roaming/Factorio/temp/currently-playing/control.lua:666: in function 'action'
core/lualib/story.lua:99: in function 'story_update'
...Data/Roaming/Factorio/temp/currently-playing/control.lua:787: in function <...Data/Roaming/Factorio/temp/currently-playing/control.lua:784>"
8099.887 Info ServerMultiplayerManager.cpp:796: updateTick(5171993) changing state from(InGame) to(Failed)
8099.887 Info SteamContext.cpp:486: Leaving lobby...
8133.355 Info ServerMultiplayerManager.cpp:140: Quitting multiplayer connection.
8133.355 Info ServerMultiplayerManager.cpp:796: updateTick(5171993) changing state from(Failed) to(Closed)
8133.513 Info UDPSocket.cpp:218: Closing socket
8133.514 Info UDPSocket.cpp:248: Socket closed
8133.514 Info UDPSocket.cpp:218: Closing socket
8133.524 Info UDPSocket.cpp:218: Closing socket
8133.524 Info UDPSocket.cpp:248: Socket closed

Information that might be relevant: I'm playing solo in a multiplayer session, but I previously started the game in single player. I have previously loaded the game from an autosave (ran myself over with a train), and no other mods are running.

Hi,

first of all, do not play the missions in the multiplayer (even when you re solo). There are scripts, which disabling things used in multiplayer. Play the mod only from Singleplayer menu.

If you have any problem to play missions in singleplayer, try to disable all other mods before you starting to play. If you disable mods in the middle of your play or loaded saves, it might still cost you trouble. :-)

Please tell me, if you still having issues. ;)