One/Some of the missions have some broken component. Test which missions are broken and remove them. This needs to be fixed though.
I'm not sure what exactly breaks this though.
One of the guys I play with said that the server crashes as soon as a player joins a server with one of the broken missions.
Also, while fixing that, they should make it possible to update missions while the server is running. No need to lock all mission files, it would be enough to lock the one that is being played/selected.
