What is base_gmodentity and why is it giving me errors

ERROR: Trying to derive entity spawned_weapon from non existant entity base_gmodentity!
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ERROR: Trying to derive entity ent_santa_hat from non existant entity base_gmodentity!
ERROR: Trying to derive entity spawned_weapon from non existant entity base_gmodentity!
ERROR: Trying to derive entity spawned_weapon from non existant entity base_gmodentity!

For some reason on an rp server, I keep getting that error

Base_gmodentity only exists in sandbox, if you don’t derive from sandbox, this entity never exists and thereby no entity can derive from that entity.

Please explain more clearly

[editline]9th January 2011[/editline]

and how do i fix it

If you are only joining a server and you are not administrating it then you can’t fix it.

If you run the server or have access to its files you can copy base_gmodentity from gamemodes/sandbox/entities/entities/ and put it into the rp’s gamemodes/RP_GAMEMODE/entities/entities/ folder.