"A fatal error has occurred, the connection is terminated" in Galacticraft

Two of my friends tried going to the moon in my server with the Galacticraft mod and many other add-ons, they got timed out right before going out of the atmosphere, and when they rejoin the error in the title occurs. Now they are stuck in outer space, unable to join

Here is a log consisting of just one of them joining and disconnecting https://mclo.gs/CyksIoO