The following exception appears in the server log when a player first travels to the moon. The player is kicked as a result.

 java.lang.NoClassDefFoundError: net/minecraft/server/integrated/IntegratedServer
    at galaxyspace.core.events.GSEventHandler.sendPlanetList(Unknown Source) ~[GSEventHandler.class:?]
    at galaxyspace.core.events.GSEventHandler.onEntityUpdate(Unknown Source) ~[GSEventHandler.class:?]
    at cpw.mods.fml.common.eventhandler.ASMEventHandler_497_GSEventHandler_onEntityUpdate_LivingUpdateEvent.invoke(.dynamic) ~[?:?]

net/minecraft/server/integrated/IntegratedServer is not available on dedicated servers. The changelog for later versions mentions no fix for this.

What server core do you use?

This was using forge-1.7.10-10.13.4.1614

I updated the Galacticraft and GalaxySpace mods and the error does not happen.

Here are the updates I made:

• GalaxySpace 1.2.1 Stable >> 1.2.3 Stable
• MicdoodleCore 1.7-3.0.12.503 >> 1.7-3.0.12.504
• Galacticraft Core 1.7-3.0.12.503 >> 1.7-3.0.12.504
• Galacticraft Planets 1.7-3.0.12.503 >> 1.7-3.0.12.504

Not sure which one fixed it but you can close this issue now.

try on Thermos